Fused tricyclic compounds, methods and compositions for inhibiting PARP activity

ABSTRACT

A compound of formula I:or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug, metabolite, stereoisomer, or mixtures thereof.

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 09/079,510, filed May 15, 1998, the contents ofwhich are incorporated herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to inhibitors of the nucleic enzymepoly(adenosine5′-diphospho-ribose)polymerase[“poly(ADP-ribose)polymerase” or “PARP”,which is also sometimes called “PARS” for poly(ADP-ribose) synthetase].More particularly, the invention relates to the use of PARP inhibitorsto prevent and/or treat tissue damage resulting from cell damage ordeath due to necrosis or apoptosis; neural tissue damage resulting fromischemia and reperfusion injury; neurological disorders andneurodegenerative diseases; to prevent or treat vascular stroke; totreat or prevent cardiovascular disorders; to treat other conditionsand/or disorders such as age-related macular degeneration, AIDS andother immune senescence diseases, arthritis, atherosclerosis, cachexia,cancer, degenerative diseases of skeletal muscle involving replicativesenescence, diabetes, head trauma, immune senescence, inflammatory boweldisorders (such as colitis and Crohn's disease), muscular dystrophy,osteoarthritis, osteoporosis, chronic and acute pain (such asneuropathic pain), renal failure, retinal ischemia, septic shock (suchas endotoxic shock), and skin aging; to extend the lifespan andproliferative capacity of cells; to alter gene expression of senescentcells; or to radiosensitize hypoxic tumor cells.

2. Description of the Prior Art

Poly(ADP-ribose) polymerase (“PARP”) is an enzyme located in the nucleiof cells of various organs, including muscle, heart and brain cells.PARP plays a physiological role in the repair of strand breaks in DNA.Once activated by damaged DNA fragments, PARP catalyzes the attachmentof up to 100 ADP-ribose units to a variety of nuclear proteins,including histones and PARP itself. While the exact range of functionsof PARP has not been fully established, this enzyme is thought to play arole in enhancing DNA repair.

During major cellular stresses, however, the extensive activation ofPARP can rapidly lead to cell damage or death through depletion ofenergy stores. Four molecules of ATP are consumed for every molecule ofNAD (the source of ADP-ribose) regenerated. Thus, NAD, the substrate ofPARP, is depleted by massive PARP activation and, in the efforts tore-synthesize NAD, ATP may also be depleted.

It has been reported that PARP activation plays a key role in both NMDA-and NO-induced neurotoxicity, as shown by the use of PARP inhibitors toprevent such toxicity in cortical cultures in proportion to theirpotencies as inhibitors of this enzyme (Zhang et al., “Nitric OxideActivation of Poly(ADP-Ribose)Synthetase in Neurotoxicity”, Science,263:687-89 (1994)); and in hippocampal slices (Wallis et al.,“Neuroprotection Against Nitric Oxide Injury with Inhibitors ofADP-Ribosylation”, NeuroReport, 5:3, 245-48 (1993)). The potential roleof PARP inhibitors in treating neurodegenerative diseases and headtrauma has thus been known. Research, however, continues to pinpoint theexact mechanisms of their salutary effect in cerebral ischemia, (Endreset al., “Ischemic Brain Injury is Mediated by the Activation ofPoly(ADP-Ribose)Polymerase”, J. Cereb. Blood Flow Metabol., 17:1143-51(1997)) and in traumatic brain injury (Wallis et al., “TraumaticNeuroprotection with Inhibitors of Nitric Oxide and ADP-Ribosylation,Brain Res., 710:169-77 (1996)).

It has been demonstrated that single injections of PARP inhibitors havereduced the infarct size caused by ischemia and reperfusion of the heartor skeletal muscle in rabbits. In these studies, a single injection ofthe PARP inhibitor, 3-amino-benzamide (10 mg/kg), either one minutebefore occlusion or one minute before reperfusion, caused similarreductions in infarct size in the heart (32-42%). Another PARPinhibitor, 1,5-dihydroxyisoquinoline (1 mg/kg), reduced infarct size bya comparable degree (38-48%). Thiemermann et al., “Inhibition of theActivity of Poly(ADP Ribose)Synthetase Reduces Ischemia-ReperfusionInjury in the Heart and Skeletal Muscle”, Proc. Natl. Acad. Sci. USA,94:679-83 (1997). This finding has suggested that PARP inhibitors mightbe able to salvage previously ischemic heart or skeletal muscle tissue.

PARP activation has also been shown to provide an index of damagefollowing neurotoxic insults by glutamate (via NMDA receptorstimulation), reactive oxygen intermediates, amyloid β-protein,n-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its activemetabolite N-methyl-4-phenylpyridine (MPP⁺), which participate inpathological conditions such as stroke, Alzheimer's disease andParkinson's disease. Zhang et al., “Poly(ADP-Ribose) SynthetaseActivation: An Early Indicator of Neurotoxic DNA Damage”, J. Neurochem.,65:3, 1411-14 (1995). Other studies have continued to explore the roleof PARP activation in cerebellar granule cells in vitro and in MPTPneurotoxicity. Cosi et al., “Poly(ADP-Ribose)Polymerase (PARP)Revisited. A New Role for an Old Enzyme: PARP Involvement inNeurodegeneration and PARP Inhibitors as Possible NeuroprotectiveAgents”, Ann. N. Y. Acad. Sci., 825:366-79 (1997); and Cosi et al.,“Poly(ADP-Ribose)Polymerase Inhibitors Protect Against MPTP-inducedDepletions of Striatal Dopamine and Cortical Noradrenaline in C57B1/6Mice”, Brain Res., 729:264-69 (1996).

Neural damage following stroke and other neurodegenerative processes isthought to result from a massive release of the excitatoryneurotransmitter glutamate, which acts upon the N-methyl-D-aspartate(NMDA) receptors and other subtype receptors. Glutamate serves as thepredominate excitatory neurotransmitter in the central nervous system(CNS). Neurons release glutamate in great quantities when they aredeprived of oxygen, as may occur during an ischemic brain insult such asa stroke or heart attack. This excess release of glutamate in turncauses over-stimulation (excitotoxicity) of N-methyl-D-aspartate (NMDA),AMPA, Kainate and MGR receptors. When glutamate binds to thesereceptors, ion channels in the receptors open, permitting flows of ionsacross their cell membranes, e.g., Ca²⁺ and Na⁺ into the cells and K⁺out of the cells. These flows of ions, especially the influx of Ca²⁺,cause overstimulation of the neurons. The over-stimulated neuronssecrete more glutamate, creating a feedback loop or domino effect whichultimately results in cell damage or death via the production ofproteases, lipases and free radicals. Excessive activation of glutamatereceptors has been implicated in various neurological diseases andconditions including epilepsy, stroke, Alzheimer's disease, Parkinson'sdisease, Amyotrophic Lateral Sclerosis (ALS), Huntington's disease,schizophrenia, chronic pain, ischemia and neuronal loss followinghypoxia, hypoglycemia, ischemia, trauma, and nervous insult. Recentstudies have also advanced a glutamatergic basis for compulsivedisorders, particularly drug dependence. Evidence includes findings inmany animal species, as well as, in cerebral cortical cultures treatedwith glutamate or NMDA, that glutamate receptor antagonists block neuraldamage following vascular stroke. Dawson et al., “Protection of theBrain from Ischemia”, Cerebrovascular Disease, 319-25 (H. Hunt Batjered., 1997). Attempts to prevent excitotoxicity by blocking NMDA, AMPA,Kainate and MGR receptors have proven difficult because each receptorhas multiple sites to which glutamate may bind. Many of the compositionsthat are effective in blocking the receptors are also toxic to animals.As such, there is no known effective treatment for glutamateabnormalities.

The stimulation of NMDA receptors, in turn, activates the enzymeneuronal nitric oxide synthase (NNOS), which causes the formation ofnitric oxide (NO), which more directly mediates neurotoxicity.Protection against NMDA neurotoxicity has occurred following treatmentwith NOS inhibitors. See Dawson et al., “Nitric Oxide Mediates GlutamateNeurotoxicity in Primary Cortical Cultures”, Proc. Natl. Acad. Sci. USA,88:6368-71 (1991); and Dawson et al., “Mechanisms of NitricOxide-mediated Neurotoxicity in Primary Brain Cultures”, J. Neurosci.,13:6, 2651-61 (1993). Protection against NMDA neurotoxicity can alsooccur in cortical cultures from mice with targeted disruption of NNOS.See Dawson et al., “Resistance to Neurotoxicity in Cortical Culturesfrom Neuronal Nitric Oxide Synthase-Deficient Mice”, J. Neurosci., 16:8,2479-87 (1996).

It is known that neural damage following vascular stroke is markedlydiminished in animals treated with NOS inhibitors or in mice with NNOSgene disruption. Iadecola, “Bright and Dark Sides of Nitric Oxide inIschemic Brain Injury”, Trends Neurosci., 20:3, 132-39 (1997); and Huanget al., “Effects of Cerebral Ischemia in Mice Deficient in NeuronalNitric Oxide Synthase”, Science, 265:1883-85 (1994). See also, Beckmanet al., “Pathological Implications of Nitric Oxide, Superoxide andPeroxynitrite Formation”, Biochem. Soc. Trans., 21:330-34 (1993). EitherNO or peroxynitrite can cause DNA damage, which activates PARP. Furthersupport for this is provided in Szabó et al., “DNA Strand Breakage,Activation of Poly(ADP-Ribose) Synthetase, and Cellular Energy Depletionare Involved in the Cytotoxicity in Macrophages and Smooth Muscle CellsExposed to Peroxynitrite”, Proc. Natl. Acad. Sci. USA, 93:1753-58(1996).

Zhang et al., U.S. Pat. No. 5,587,384 issued Dec. 24, 1996, discussesthe use of certain PARP inhibitors, such as benzamide and1,5-dihydroxy-isoquinoline, to prevent NMDA-mediated neurotoxicity and,thus, treat stroke, Alzheimer's disease, Parkinson's disease andHuntington's disease. However, it is has now been discovered that Zhanget al. may have been in error in classifying neurotoxicity asNMDA-mediated neurotoxicity. Rather, it may have been more appropriateto classify the in vivo neurotoxicity present as glutamateneurotoxicity. See Zhang et al. “Nitric Oxide Activation ofPoly(ADP-Ribose)Synthetase in Neurotoxicity”, Science, 263:687-89(1994). See also, Cosi et al., Poly(ADP-Ribose)Polymerase InhibitorsProtect Against MPTP-induced Depletions of Striatal Dopamine andCortical Noradrenaline in C57B1/6 Mice”, Brain Res., 729:264-69 (1996).

It is also known that PARP inhibitors affect DNA repair generally.Cristovao et al., “Effect of a. Poly(ADP-Ribose)Polymerase Inhibitor onDNA Breakage and Cytotoxicity Induced by Hydrogen Peroxide andγ-Radiation,” Terato., Carcino., and Muta., 16:219-27 (1996), discussesthe effect of hydrogen peroxide and γ-radiation on DNA strand breaks inthe presence of and in the absence of 3-aminobenzamide, a potentinhibitor of PARP. Cristovao et al. observed a PARP-dependent recoveryof DNA strand breaks in leukocytes treated with hydrogen peroxide.

PARP inhibitors have been reported to be effective in radiosensitizinghypoxic tumor cells and effective in preventing tumor cells fromrecovering from potentially lethal damage of DNA after radiationtherapy, presumably by their ability to prevent DNA repair. See U.S.Pat. Nos. 5,032,617; 5,215,738; and 5,041,653.

Evidence also exists that PARP inhibitors are useful for treatinginflammatory bowel disorders. Salzman et al., “Role of Peroxynitrite andPoly(ADP-Ribose)Synthase Activation Experimental Colitis,” Japanese J.Pharm., 75, Supp. I:15 (1997), discusses the ability of PARP inhibitorsto prevent or treat colitis. Colitis was induced in rats by intraluminaladministration of the hapten trinitrobenzene sulfonic acid in 50%ethanol. Treated rats received 3-aminobenzamide, a specific inhibitor ofPARP activity. Inhibition of PARP activity reduced the inflammatoryresponse and restored the morphology and the energetic status of thedistal colon. See also, Southan et al., “Spontaneous Rearrangement ofAminoalkylithioureas into Mercaptoalkylguanidines, a Novel Class ofNitric Oxide Synthase Inhibitors with Selectivity Towards the InducibleIsoform”, Br. J. Pharm., 117:619-32 (1996); and Szabó et al.,“Mercaptoethylguanidine and Guanidine Inhibitors of Nitric OxideSynthase React with Peroxynitrite and Protect AgainstPeroxynitrite-induced Oxidative Damage”, J. Biol. Chem., 272:9030-36(1997).

Evidence also exists that PARP inhibitors are useful for treatingarthritis. Szabó et al., “Protective Effects of an Inhibitor ofPoly(ADP-Ribose)Synthetase in Collagen-Induced Arthritis,” Japanese J.Pharm., 75, Supp. I:102 (1997), discusses the ability of PARP inhibitorsto prevent or treat collagen-induced arthritis. See also Szabó et al.,“DNA Strand Breakage, Activation of Poly(ADP-Ribose)Synthetase, andCellular Energy Depletion are Involved in the Cytotoxicity inMacrophages and Smooth Muscle Cells Exposed to Peroxynitrite,” Proc.Natl. Acad. Sci. USA, 93:1753-58 (March 1996); Bauer et al.,“Modification of Growth Related Enzymatic Pathways and Apparent Loss ofTumorigenicity of a ras-transformed Bovine Endothelial Cell Line byTreatment with 5-Iodo-6-amino-1,2-benzopyrone (INH₂BP)”, Intl. J.Oncol., 8:239-52 (1996); and Hughes et al., “Induction of T Helper CellHyporesponsiveness in an Experimental Model of Autoimmunity by UsingNonmitogenic Anti-CD3 Monoclonal Antibody”, J. Immuno., 153:3319-25(1994).

Further, PARP inhibitors appear to be useful for treating diabetes.Heller et al., “Inactivation of the Poly(ADP-Ribose)Polymerase GeneAffects Oxygen Radical and Nitric Oxide Toxicity in Islet Cells,” J.Biol. Chem., 270:19, 11176-80 (May 1995), discusses the tendency of PARPto deplete cellular NAD+ and induce the death of insulin-producing isletcells. Heller et al. used cells from mice with inactivated PARP genesand found that these mutant cells did not show NAD+ depletion afterexposure to DNA-damaging radicals. The mutant cells were also found tobe more resistant to the toxicity of NO.

Further still, PARP inhibitors have been shown to be useful for treatingendotoxic shock or septic shock. Zingarelli et al., “Protective Effectsof Nicotinamide Against Nitric Oxide-Mediated Delayed Vascular Failurein Endotoxic Shock: Potential Involvement of PolyADP RibosylSynthetase,” Shock, 5:258-64 (1996), suggests that inhibition of the DNArepair cycle triggered by poly(ADP ribose) synthetase has protectiveeffects against vascular failure in endotoxic shock. Zingarelli et al.found that nicotinamide protects against delayed, NO-mediated vascularfailure in endotoxic shock. Zingarelli et al. also found that theactions of nicotinamide may be related to inhibition of the NO-mediatedactivation of the energy-consuming DNA repair cycle, triggered bypoly(ADP ribose) synthetase. See also, Cuzzocrea, “Role of Peroxynitriteand Activation of Poly(ADP-Ribose)Synthetase in the Vascular FailureInduced by Zymosan-activated Plasma,” Brit. J. Pharm., 122:493-503(1997).

Yet another known use for PARP inhibitors is treating cancer. Suto etal., “Dihydroisoquinolinones: The Design and Synthesis of a New Seriesof Potent Inhibitors of Poly(ADP-Ribose)Polymerase”, Anticancer DrugDes., 7:107-17 (1991), discloses processes for synthesizing a number ofdifferent PARP inhibitors. In addition, Suto et al., U.S. Pat. No.5,177,075, discusses several isoquinolines used for enhancing the lethaleffects of ionizing radiation or chemotherapeutic agents on tumor cells.Weltin et al., “Effect of 6(5H)-Phenanthridinone, an Inhibitor ofPoly(ADP-ribose)Polymerase, on Cultured Tumor Cells”, Oncol. Res., 6:9,399-403 (1994), discusses the inhibition of PARP activity, reducedproliferation of tumor cells, and a marked synergistic effect when tumorcells are co-treated with an alkylating drug.

Still another use for PARP inhibitors is the treatment of peripheralnerve injuries, and the resultant pathological pain syndrome known asneuropathic pain, such as that induced by chronic constriction injury(CCI) of the common sciatic nerve and in which transsynaptic alterationof spinal cord dorsal horn characterized by hyperchromatosis ofcytoplasm and nucleoplasm (so-called “dark” neurons) occurs. See Mao etal., Pain, 72:355-366 (1997).

PARP inhibitors have also been used to extend the lifespan andproliferative capacity of cells including treatment of diseases such asskin aging, Alzheimer's disease, atherosclerosis, osteoarthritis,osteoporosis, muscular dystrophy, degenerative diseases of skeletalmuscle involving replicative senescence, age-related maculardegeneration, immune senescence, AIDS, and other immune senescencediseases; and to alter gene expression of senescent cells. See WO98/27975.

Large numbers of known PARP inhibitors have been described in Banasik etal., “Specific Inhibitors of Poly(ADP-Ribose)Synthetase andMono(ADP-Ribosyl)-Transferase”, J. Biol. Chem., 267:3, 1569-75 (1992),and in Banasik et al., “Inhibitors and Activators of ADP-RibosylationReactions”, Molec. Cell. Biochem., 138:185-97 (1994).

However, the approach of using these PARP inhibitors in the waysdiscussed above has been limited in effect. For example, side effectshave been observed with some of the best-known PARP inhibitors, asdiscussed in Milam et al., “Inhibitors of Poly(AdenosineDiphosphate-Ribose) Synthesis: Effect on Other Metabolic Processes”,Science, 223:589-91 (1984). Specifically, the PARP inhibitors3-aminobenzamide and benzamide not only inhibited the action of PARP butalso were shown to affect cell viability, glucose metabolism, and DNAsynthesis. Thus, it was concluded that the usefulness of these PARPinhibitors may be severely restricted by the difficulty of finding adose that will inhibit the enzyme without producing additional metaboliceffects.

Nitrogen-containing tricyclic compounds other than the compounds of theinvention are known:

Philipp et al. discloses3,4-dihydropyrrolo[4,3,2-de]isoquinolin-5(1H)-one, which has thefollowing formula:

Philipp et al., U.S. Pat. No. 3,978,066, issued Aug. 31, 1976; Philippet al., U.S. Pat. No. 3,900,477, issued Aug. 19, 1975; and Philipp etal., U.S. Pat. No. 3,950,343, issued Apr. 13, 1976. The compound istaught as an intermediate for the preparation of compounds disclosed ashaving circulatory and central nervous system activities, this causingantidepressant and antihypertensive effects.

The above Philipp et al. patents also disclose pyrroloisoquinolinederivatives having the following formula:

wherein R¹ is amino, lower alkylamino, di(lower)alkylamino ordi(lower)alkylamino(lower)alkylamino. The compounds are disclosed ashaving circulatory and central nervous system activities that elicitantidepressant and antihypertensive effects.

Philipp et al., U.S. Pat. No. 3,950,343, issued Apr. 13, 1976, alsodiscloses compounds having the following formula:

wherein R₁ and R₂ each are hydrogen, lower alkyl, ordi(lower)alkylamino(lower)alkyl. The compounds are disclosed as havingcirculatory and central nervous system activities that elicitantidepressant and antihypertensive effects.

1,4-Dihydro-benzo[C]-1,5-naphthyridin-2(3H)-ones having the formula:

wherein X is hydrogen, halogen, lower alkyl, lower alkoxy,trifluoromethyl or hydroxy, are disclosed by Martin et al., U.S. Pat.No. 4,742,171, issued May 3, 1988. Martin et al. disclosesnaphthyridones that are said to be useful in the treatment of variousmemory dysfunctions characterized by decreased cholinergic function,such as Alzheimer's disease.

Pyracridones are shown in Rath, U.S. Pat. No. 1,895,105, issued Jan. 24,1933. Rath discloses three-ring pyracridones having the formula:

wherein the Xs can be amino or nitro groups.

Petrow, U.S. Pat. No. 2,467,692, issued Apr. 19, 1949, disclosesnaphthyridones having the formula:

The Petrow compounds are purported to possess “valuable therapeuticproperties”.

4-Alkyl(or Alkenyl)-1,4-dihydro-1-oxo-benzo[f][1,7]-naphthyridine2-carboxylic acid derivatives are shown in G. Lesher, U.S. Pat. No.3,300,499, issued Jan. 24, 1967. These compounds have the formula:

wherein X is a member selected from the group consisting of carboxy andlower-carbalkoxy, and R₁ is a member selected from the group consistingof lower alkyl and lower alkenyl. The compounds are said to haveantibacterial properties.

2,3,7,8,9,9a-Hexahydro-1H-benzo[d,e][1,7]-naphthyridine derivatives areshown in L. Humber, U.S. Pat. No. 3,557,119, issued Jan. 19, 1971.Humber discloses benzo-naphthyridone derivatives having the formula:

wherein R₁ and R₂ are selected from the group consisting of hydrogen,hydroxyl and lower alkoxy, wherein R₃ is selected from the groupconsisting of hydrogen, lower alkyl, phenyl and phenyl(lower alkyl),wherein R₅ is selected from the group consisting of hydrogen and loweralkyl, and wherein R₄ and R₆ are selected from the group consisting ofhydrogen, lower alkyl and other substituents as listed in the patent.The compounds are said to have antibacterial activity.

3,4-Dihydrobenzo(B)-(1,7)-naphthyridin-1(2H)-one is shown in E. Watson,U.S. Pat. No. 3,700,673, issued Oct. 24, 1972. Watson disclosesbenzonaphthyridinones having the formula:

wherein R is hydroxy, phenoxy, chloro, amino, (lower)alkylamino anddi(lower)alkylamino, wherein Ris hydrogen or acetyl, R₂ and R₃ arehydrogen or methoxy and R₄ is hydrogen, methoxy or dimethylamino. Thecompounds are said to be antispasmodic agents that abolish spasticcontractions and lower hypertonicity of the ileum and colon.

1,2,3,4-Tetrahydro-8,9-dimethoxy-benzo[c][2,7]-naphthyridin-5(6H)-onehydrochloride is shown in Brown et al., U.S. Pat. No. 3,991,064, issuedNov. 9, 1976. Brown et al. discloses benzonaphthyridines having theformula:

wherein R₁ and R₂ are hydrogen, lower alkyl, lower alkoxy or cometogether to form a methylenedioxy group, wherein R₃ is hydrogen or loweralkyl, and wherein R₄ is hydrogen or a cycloalkyl-lower alkylsubstituent. The compounds are said to be bronchodilators

Non-azo N-substituted-1,8-naphthalimide derivatives are shown in Lewiset al., U.S. Pat. No. 5,420,136, issued May 30, 1995. Lewis et al.discloses naphthalimide dyes having the following formula or relatedformulas:

wherein X is halogen, sulfonate ester or a nitrogen leaving group, and Rand R′ are alkyl or particular groups capable of completing with a metalion (as defined in the patent).

Pyrrolo[4,3,2-de]quinolin-8(1H)-ones are shown in Ireland et al., U.S.Pat. No. 5,414,001, issued May 9, 1995. Ireland et al. disclosesanti-neoplastic pyrroloquinolinones having the formula:

The compounds are said to be useful for treating tumors and bacterialinfections.

1,2,3,5-Tetrahydroimidezo(2,1-b)quinazolin-2-ones and 6(H)-1,2,3,4-tetrahydropyimido(2,1-b) quinazolin-2-ones are shown inBeverung, Jr. et al., U.S. Pat. No. Re. 31,617, published Jun. 26, 1984.Beverung, Jr. et al. discloses quinazolinone derivatives having theformula:

The Beverung, Jr. et al. compounds are useful in the control ofhypertension, as anti-clotting agents and as bronchodilators.

Ethyl 5,6-dihydro-1-oxo-1H-pyrimido[1,2-a]-quinoxaline-2-carboxylate isshown in Kennewell et al., U.S. Pat. No. 4,472,401, issued Sep. 18,1984. Kennewal et al. discloses quinoxaline derivatives having theformula:

The Kennewell et al. compounds are said to have antiallergic properties.

Benzo[5,6]pyrano[2,3,4-ij]quinolizine and Benzo[5,6]thiopyrano,[2,3,4-ij]quinolizine derivatives are shown in Chu et al., U.S. Pat. No.5,618,813, issued Apr. 8, 1997. Chu et al. disclosesbenzopyranoquinolizine and benzothiopyranoquinolizine derivatives havingthe formula:

The Chu et al. compounds are said to have antibacterial andantineoplastic activities.

Descarboxylsergic acids and ergolinones such as6-methyl-9-ergoline-8-ones are shown in Bach et al., U.S. Pat. No.4,031,097, issued Jun. 21, 1977. Bach et al. discloses compounds havingthe formula:

The Bach et al. compounds are said to have oxytocic, serotoninantagonist, prolactin inhibition and muscle contracting activities.

It is not believed that the above disclosed compounds have been shown toinhibit PARP activity per se.

SUMMARY OF THE INVENTION

The compounds of the present invention have formula I:

or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug,metabolite, stereoisomer, or mixtures thereof, wherein:

Y represents the atoms necessary to form a fused 5- to 6-membered,aromatic or non-aromatic, carbocyclic or heterocyclic ring, wherein Yand any heteroatom(s) therein is unsubstituted or independentlysubstituted with at least one non-interfering hydroxy, amino, nitro,dimethylamino, alkylamino, alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl substituent;

R¹ and R³ are independently hydrogen, alkyl, halo, alkenyl, cycloalkyl,cycloalkenyl, aralkyl, aryl, double bonded oxygen, —COOR⁵, or a moietyselected from the group consisting of:

wherein R⁷ is alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aryl;

R², when present, is hydrogen, alkyl, alkenyl, amino, cycloalkyl,cycloalkenyl, aralkyl or aryl;

R⁴, R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, cycloalkyl,cycloalkenyl, aralkyl or aryl; wherein R², R⁴, R⁵ and R⁶ areunsubstituted or independently substituted with a moiety selected fromthe group consisting of alkyl, alkenyl, alkoxy, phenoxy, benzyloxy,cycloalkyl, cycloalkenyl, hydroxy, carboxy, carbonyl, amino,dimethylamino, alkylamino, amido, cyano, isocyano, nitro, nitroso,nitrilo, isonitrilo, imino, azo, diazo, sulfonyl, sulfoxy, thio,thiocarbonyl, alkylthio, sulfhydryl, halo, haloalkyl, trifluoromethyland aryl; provided that:

(i) when R¹, R², R⁴, R⁵ and R⁶ are each hydrogen and Y is a 5-membered,unsaturated, heterocyclic ring containing a nitrogen as its soleheteroatom, R³ is not double bonded oxygen;

(ii) when R¹, R⁴, R⁵ and R⁶ are each hydrogen, R² is hydrogen or loweralkyl, and Y is a 5-membered, unsaturated, heterocyclic ring containinga nitrogen as its sole heteroatom, R³ is not hydrogen;

(iii) when R⁴, R⁵ and R⁶ are each hydrogen, R² is hydrogen or loweralkyl, R³ is hydrogen, lower alkyl or phenyl, and Y is a 6-membered,non-aromatic, heterocyclic ring containing a nitrogen as its soleheteroatom, R¹ is not hydrogen;

(iv) when R² is alkyl or aryl, R³ is double bonded oxygen, and Y is a6-membered, carbocyclic, unsaturated ring, R¹ is not double bondedoxygen;

(v) when R¹, R³, R⁴, R⁵ and R⁶ are each hydrogen, and Y forms afive-membered N-containing ring, then R² is not hydrogen or alkyl; and

(vi) when R², R⁴, R⁵ and R⁶ are each hydrogen, and Y is phenyl, thenboth R¹ and R³ cannot be double bonded oxygen.

In an additional embodiment, a process for making the compound offormula I comprises the step of contacting an intermediate of formulaII:

with NH₂R², wherein Y, R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are as definedabove for formula I.

In yet another embodiment, the pharmaceutical composition of theinvention comprises a pharmaceutically acceptable carrier and a compoundof formula I:

or a pharmaceutically acceptable salt, hydrate, ester solvate, prodrug,metabolite, stereoisomer, or mixtures thereof, wherein:

Y represents the atoms necessary to form a fused 5- to 6-membered,aromatic or non-aromatic, carbocyclic or heterocyclic ring, wherein Yand any heteroatom(s) therein is unsubstituted or independentlysubstituted with at least one non-interfering hydroxy, amino, nitro,dimethylamino, alkylamino, alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl substituent;

R¹ and R³ are independently hydrogen, alkyl, halo, alkenyl, cycloalkyl,cycloalkenyl, aralkyl, aryl, double bonded oxygen, —COOR⁵, or a moietyselected from the group consisting of:

wherein

R⁷ is alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aryl;

R², when present, is hydrogen, alkyl, alkenyl, amino, cycloalkyl,cycloalkenyl, aralkyl or aryl;

R⁴, R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, cycloalkyl,cycloalkenyl, aralkyl or aryl; wherein R², R⁴, R⁵ and R⁶ areunsubstituted or independently substituted with a moiety selected fromthe group consisting of alkyl, alkenyl, alkoxy, phenoxy, benzyloxy,cycloalkyl, cycloalkenyl, hydroxy, carboxy, carbonyl, amino,dimethylamino, alkylamino, amido, cyano, isocyano, nitro, nitroso,nitrilo, isonitrilo, imino, azo, diazo, sulfonyl, sulfoxy, thio,thiocarbonyl, alkylthio, sulfhydryl, halo, haloalkyl, trifluoromethyland aryl.

In a still further embodiment of the invention, the pharmaceuticalcomposition of the invention comprises a pharmaceutically acceptablecarrier and a compound of formula I:

or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug,metabolite, stereoisomer, or mixtures thereof, and a pharmaceuticallyacceptable carrier, wherein the compound of formula I is present in anamount that is sufficient to inhibit PARP activity, to treat or preventtissue damage resulting from cell damage or death due to necrosis orapoptosis, to effect a neuronal activity not mediated by NMDA toxicity,to effect a neuronal activity mediated by NMDA toxicity, to treat neuraltissue damage resulting from ischemia and reperfusion injury,neurological disorders and neurodegenerative diseases; to prevent ortreat vascular stroke; to treat or prevent cardiovascular disorders; totreat other conditions and/or disorders such as age-related maculardegeneration, AIDS and other immune senescence diseases, arthritis,atherosclerosis, cachexia, cancer, degenerative diseases of skeletalmuscle involving replicative senescence, diabetes, head trauma, immunesenescence, inflammatory bowel disorders (such as colitis and Crohn'sdisease), muscular dystrophy, osteoarthritis, osteoporosis, chronicand/or acute pain (such as neuropathic pain), renal failure, retinalischemia, septic shock (such as endotoxic shock), and skin aging; toextend the lifespan and proliferative capacity of cells; to alter geneexpression of senescent cells; or to radiosensitize hypoxic tumor cells,and wherein:

Y represents the atoms necessary to form a fused 5- to 6-membered,aromatic or non-aromatic, carbocyclic or heterocyclic ring, wherein Yand any heteroatom(s) therein is unsubstituted or independentlysubstituted with at least one non-interfering hydroxy, amino, nitro,dimethylamino, alkylamino, alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl substituent;

R¹ and R³ are independently hydrogen, alkyl, halo, alkenyl, cycloalkyl,cycloalkenyl, aralkyl, aryl, double bonded oxygen, —COOR⁵, or a moietyselected from the group consisting of:

wherein

R⁷ is alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aryl;

R², when present, is hydrogen, alkyl, alkenyl, amino, cycloalkyl,cycloalkenyl, aralkyl or aryl;.

R⁴, R⁵ and R⁶ are independently hydrogen, alkyl, alkenyl, cycloalkyl,cycloalkenyl, aralkyl or aryl; wherein R², R⁴, R⁵ and R⁶ areunsubstituted or independently substituted with a moiety selected fromthe group consisting of alkyl, alkenyl, alkoxy, phenoxy, benzyloxy,cycloalkyl, cycloalkenyl, hydroxy, carboxy, carbonyl, amino,dimethylamino, alkylamino, amido, cyano, isocyano, nitro, nitroso,nitrilo, isonitrilo, imino, azo, diazo, sulfonyl, sulfoxy, thio,thiocarbonyl, alkylthio, sulfhydryl, halo, haloalkyl, trifluoromethyland aryl.

In an additional embodiment, a method of inhibiting PARP activitycomprises administering a compound of formula I, as described above forthe pharmaceutical compositions of the invention. In yet furtherembodiments, the amount of the compound administered in the methods ofthe invention is sufficient for treating tissue damage resulting fromcell damage or death due to necrosis or apoptosis, neural tissue damageresulting from ischemia and reperfusion injury, or neurologicaldisorders and neurodegenerative diseases; to prevent or treat vascularstroke; to treat or prevent cardiovascular disorders; to treat otherconditions and/or disorders such as age-related macular degeneration,AIDS and other immune senescence diseases, arthritis, atherosclerosis,cachexia, cancer, degenerative diseases of skeletal muscle involvingreplicative senescence, diabetes, head trauma, immune senescence,inflammatory bowel disorders (such as colitis and Crohn's disease),muscular dystrophy, osteoarthritis, osteoporosis, chronic and/or acutepain (such as neuropathic pain), renal failure, retinal ischemia, septicshock (such as endotoxic shock), and skin aging; to extend the lifespanand proliferative capacity of cells; to alter gene expression ofsenescent cells; or to radiosensitize hypoxic tumor cells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the distribution of the cross-sectional infarct area atrepresentative levels along the rostrocaudal axis, as measured from theinteraural line in non-treated animals and in animals treated with 10mg/kg of 3,4-dihydro-5-[4-(1-piperidinyl)-butoxyl]-1(2H)-isoquinolinone.

FIG. 2 shows the effect of intraperitoneal administration of3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone on theinfarct volume.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the present invention inhibit PARP activity. As such,they may treat or prevent neural tissue damage resulting from celldamage or death due to necrosis or apoptosis, cerebral ischemia andreperfusion injury or neurodegenerative diseases in an animal; they mayextend the lifespan and proliferative capacity of cells and thus be usedto treat or prevent diseases associated therewith; they may alter geneexpression of senescent cells; and they may radiosensitize hypoxic tumorcells. Preferably, the compounds of the invention treat or preventtissue damage resulting from cell damage or death due to necrosis orapoptosis, and/or effect neuronal activity, either mediated or notmediated by NMDA toxicity. These compounds are thought to interfere withmore than the glutamate neurotoxicity and NO-mediated biologicalpathways. Further, the compounds of the invention can treat or preventother tissue damage related to PARP activation.

For example, the compounds of the invention can treat or preventcardiovascular tissue damage resulting from cardiac ischemia orreperfusion injury. Reperfusion injury, for instance, occurs at thetermination of cardiac bypass procedures or during cardiac arrest whenthe heart, once prevented from receiving blood, begins to reperfuse.

The compounds of the present invention can also be used to extend orincrease the lifespan or proliferation of cells and thus to treat orprevent diseases associated therewith and induced or exacerbated bycellular senescence including skin aging, atherosclerosis,osteoarthritis, osteoporosis, muscular dystrophy, degenerative diseasesof skeletal muscle involving replicative senescence, age-related maculardegeneration, immune senescence, AIDS and other immune senescencediseases, and other diseases associated with cellular senescence andaging, as well as to alter the gene expression of senescent cells. Thesecompounds can also be used to treat cancer and to radiosensitize hypoxictumor cells to render the tumor cells more susceptible to radiationtherapy and to prevent the tumor cells from recovering from potentiallylethal damage of DNA after radiation therapy, presumably by theirability to prevent DNA repair. The compounds of the present inventioncan be used to prevent or treat vascular stroke; to treat or preventcardiovascular disorders; to treat other conditions and/or disorderssuch as age-related macular degeneration, AIDS and other immunesenescence diseases, arthritis, atherosclerosis, cachexia, cancer,degenerative diseases of skeletal muscle involving replicativesenescence, diabetes, head trauma, immune senescence, inflammatory boweldisorders (such as colitis and Crohn's disease), muscular dystrophy,osteoarthritis, osteoporosis, chronic and/or acute pain (such asneuropathic pain), renal failure, retinal ischemia, septic shock (suchas endotoxic shock), and skin aging.

Preferably, the compounds of the invention act as PARP inhibitors totreat or prevent tissue damage resulting from cell death or damage dueto necrosis or apoptosis; to treat or prevent neural tissue damageresulting from cerebral ischemia and reperfusion injury orneurodegenerative diseases in an animal; to extend and increase thelifespan and proliferative capacity of cells; to alter gene expressionof senescent cells; and to radiosensitize tumor cells. These compoundsare thought to interfere with more than the NMDA-neurotoxicity andNO-mediated biological pathways. Preferably, the compounds of theinvention exhibit an IC₅₀ for inhibiting PARP in vitro of about 100 uMor lower, more preferably, about 25 uM or lower.

The compound of the invention has the formula:

or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug,metabolite, stereoisomer, or mixtures thereof, wherein: Y represents theatoms necessary to form a fused 5- to 6-membered, aromatic ornon-aromatic, carbocyclic or heterocyclic ring, wherein Y and anyheteroatom(s) therein is unsubstituted or independently substituted withat least one non-interfering alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl substituent.

When Y forms a fused 5-membered carbocyclic ring, examples thereofinclude such rings as fused cyclopentane, cyclopentene, cyclopentadieneand the like. When Y forms a 5-membered heterocyclic ring, examplesthereof include such rings as fused pyrrole, isopyrrole, imidazole,isoimidazole, pyrazole, pyrrolidine, pyrroline, imidazolidine,imidazoline, pyrazolidine, pyrazoline, isothiazole, isoxazole, furazan,furan, thiophene, 1,2,3-triazole, 1,2,4-triazole, dithiole, oxathiole,isoxazole, oxazole, thiazole, isothiazole, oxadiazole, oxatriazole,dioxazole, oxathiazole and the like ring structures.

When Y forms a fused 6-membered carbocyclic ring, examples thereofinclude such rings as fused cyclohexane, cyclohexene, benzene and thelike nuclei, optionally substituted with additional fused rings, thusforming, for example, naphthalene, anthracene, phenanthrene,benzonaphthene, and the like ring systems. When Y forms a 6-memberedheterocyclic ring, examples thereof include such rings as pyridine,pyrazine, pyrimidine, pyridazine, piperidine, piperazine, morpholine,pyran, pyrone, dioxin, triazine, oxazine, isoxazine, oxathiazine,oxadiazine, and the like rings.

Y may be aromatic, such as pyrrole, benzene or pyridine, ornon-aromatic, such as cyclopentene, piperidyl or piperazinyl.

Y may be unsubstituted or substituted with one or more non-interferingsubstituents. For example, Y may be substituted with hydroxy, amino,dimethylamino, alkylamino, dimethylamino, with an alkyl group such asmethyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl,tert-butyl, n-pentyl, 2-methylpentyl, 2-methylhexyl, dodecyl, octadecyland the like; with an alkenyl group such as ethenyl, propenyl, butenyl,pentenyl, 2-methylpentenyl, vinyl, isopropenyl, 2,2-dimethyl-1-propenyl,decenyl, hexadecenyl and the like; with an alkynyl group such asethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl and thelike; with an alkanoyl group such as formyl, acetyl, propanoyl,butanoyl, pentanoyl, benzoyl and the like; with a cycloalkyl group suchas cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctanyl,cyclononyl, cyclodecyl and the like; with a cycloalkenyl group such ascyclopropenyl, cyclopentadienyl, cyclohexenyl, cyclooctenyl and thelike; with an aralkyl group such as benzyl, 3-(1)-naphthyl-1-propyl,p-halobenzyl, p-ethylbenzyl, 1-phenyl-1-propyl, 3-pyridinyl-1-propyl,1-phenyl-2-sec-butyl, 4-phenyl-4-methyl-1-pentyl and the like; or withan aryl group, such as phenyl, naphthyl, pyridinyl, thienyl and thelike.

“Aryl” is defined as an unsaturated carbocyclic or heterocyclic moietywhich may be either unsubstituted or substituted with one or morenon-interfering substituent(s) Examples include, without limitation,phenyl, benzyl, naphthyl, indenyl, azulenyl, fluorenyl, anthracenyl,indolyl, isoindolyl, indolinyl, benzo-furanyl, benzothiophenyl,indazolyl, benzimidazolyl, benzithiazolyl, tetrahydrofurnayl,tetrahydropyranyl, pyridyl, pyrrolyl, pyrrolidinyl, pyridinyl,pyrimidinyl, purinyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl,quinolizinyl, furyl, thiophenyl, imidazolyl, oxazolyl, benzoxazolyl,thiazolyl, isoxazolyl, isotriazolyl, oxadiazolyl, triazolyl,thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazolyl, pyrazolinyl,pyrazolidinyl, thienyl, tetrahydroisoquinolinyl, cinnolinyl,phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, pteridinyl,carbozolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl and thelike.

Possible substituents on an aryl group can be any non-interferingsubstituent. However, preferred substituents include, withoutlimitation, alkyl, alkenyl, alkoxy, phenoxy, benzyloxy, cycloalkyl,cycloalkenyl, hydroxy, carboxy, carbonyl, amino, dimethylamino,alkylamino, amido, cyano, isocyano, nitro, nitroso, nitrilo, isonitrilo,imino, azo, diazo, sulfonyl, sulfoxy, thio, thiocarbonyl, alkylthio,sulfhydryl, halo, haloalkyl, trifluoromethyl and aryl. Examples ofaralkyl groups include benzyl, 3-(1)-naphthyl-1-propyl, p-halobenzyl,p-ethylbenzyl, 1-phenyl-1-propyl, 3-pyridinyl-1-propyl,1-phenyl-2-sec-butyl, 4-phenyl-4-methyl-1-pentyl and the like.

Specific examples of useful Y structures are shown below:

In a preferred embodiment, however, Y has at least one site ofunsaturation. More preferably Y forms a fused benzene ring.

R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ may be hydrogen, hydroxy, nitro, amino,alkylamino, dimethylamino, alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl. Examples of these groups are shown above as possiblesubstituents on ring Y.

Examples of useful amino groups include NH₂, methylamino, ethylamino,dimethylamino, diethylamino, propylamino, butylamino, pentylamino,hexylamino and arylamino.

In addition, R¹ and R³ may also be halo, double bonded oxygen,carboxylic acid (—COOH), carboxylic acid analogues (e.g., —COOR) orcarboxylic acid mimics. Examples of carboxylic acid mimics include:

wherein R⁷ is alkyl, alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aryl,examples of which are shown above as possible Y substituents. R⁷ itselfmay also be unsubstituted or substituted with one or morenon-interfering substituents, such as the alkyl, alkenyl, cycloalkyl andcycloalkenyl groups described above. The above carboxylic acid mimicsare shown in R. Silverman, The Organic Chemistry of Drug Design and DrugAction, Academic Press (1992).

In the compound of the invention, examples of the tricyclic nuclear ringstructure include the following:

or the pharmaceutically acceptable salts, hydrates, esters, solvates,prodrugs, metabolites, stereoisomers, or mixtures thereof.

Specific examples of preferred embodiments are shown below:

Also included are the pharmaceutically acceptable salts, hydrates,esters, solvates, prodrugs, metabolites, and stereoisomers thereof. Amost preferred embodiment is2,3,3a,9b-tetrahydro-1H-benzo[de]isoquinolin-1-one which has thefollowing structure:

The compounds of the invention may be useful in a free base form, in theform of pharmaceutically acceptable salts, pharmaceutically acceptablehydrates, pharmaceutically acceptable esters, pharmaceuticallyacceptable solvates, pharmaceutically acceptable prodrugs,pharmaceutically acceptable metabolites, and in the form ofpharmaceutically acceptable stereoisomers. These forms are all withinthe scope of the invention. In practice, the use of these forms amountsto use of the neutral compound. “Pharmaceutically acceptable salt”,“hydrate”, “ester” or “solvate” refers to a salt, hydrate, ester, orsolvate of the inventive compounds which possesses the desiredpharmacological activity and which is neither biologically nor otherwiseundesirable. Organic acids can be used to produce salts, hydrates,esters, or solvates such as acetate, adipate, alginate, aspartate,benzoate, benzenesulfonate, p-toluenesulfonate, bisulfate, sulfamate,sulfate, naphthylate, butyrate, citrate, camphorate, camphorsulfonate,cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate,fumarate, glucoheptanoate, glycerophosphate, hemisulfate heptanoate,hexanoate, 2-hydroxyethanesulfonate, lactate, maleate, methanesulfonate,2-naphthalenesulfonate, nicotinate, oxalate, tosylate and undecanoate.Inorganic acids can be used to produce salts, hydrates, esters, orsolvates such as hydrochloride, hydrobromide, hydroiodide, andthiocyanate.

Examples of suitable base salts, hydrates, esters, or solvates includehydroxides, carbonates, and bicarbonates of ammonia, alkali metal saltssuch as sodium, lithium and potassium salts, alkaline earth metal saltssuch as calcium and magnesium salts, aluminum salts, and zinc salts.

Salts, hydrates, esters, or solvates may also be formed with organicbases. Organic bases suitable for the formation of pharmaceuticallyacceptable base addition salts, hydrates, esters, or solvates of thecompounds of the present invention include those that are non-toxic andstrong enough to form such salts, hydrates, esters, or solvates. Forpurposes of illustration, the class of such organic bases may includemono-, di-, and trialkylamines, such as methylamine, dimethylamine,triethylamine and dicyclohexylamine; mono-, di- ortrihydroxyalkylamines, such as mono-, di-, and triethanolamine; aminoacids, such as arginine and lysine; guanidine; N-methyl-glucosamine;N-methyl-glucamine; L-glutamine; N-methyl-piperazine; morpholine;ethylenediamine; N-benzyl-phenethylamine;(trihydroxy-methyl)aminoethane; and the like. See, for example,“Pharmaceutical Salts,” J. Pharm. Sci., 66:1, 1-19 (1977). Accordingly,basic nitrogen-containing groups can be quaternized with agentsincluding: lower alkyl halides such as methyl, ethyl, propyl, and butylchlorides, bromides and iodides; dialkyl sulfates such as dimethyl,diethyl, dibutyl and diamyl sulfates; long chain halides such as decyl,lauryl, myristyl and stearyl chlorides, bromides and iodides; andaralkyl halides such as benzyl and phenethyl bromides.

The acid addition salts, hydrates, esters, or solvates of the basiccompounds may be prepared either by dissolving the free base of a PARPinhibitor in an aqueous or an aqueous alcohol solution or other suitablesolvent containing the appropriate acid or base, and isolating the saltby evaporating the solution. Alternatively, the free base of the PARPinhibitor may be reacted with an acid, as well as reacting the PARPinhibitor having an acid group thereon with a base, such that thereactions are in an organic solvent, in which case the salt separatesdirectly or can be obtained by concentrating the solution.

“Pharmaceutically acceptable prodrug” refers to a derivative of theinventive compounds which undergoes biotransformation prior toexhibiting its pharmacological effect(s). The prodrug is formulated withthe objective(s) of improved chemical stability, improved patientacceptance and compliance, improved bioavailability, prolonged durationof action, improved organ selectivity, improved formulation (e.g.,increased hydrosolubility), and/or decreased side effects (e.g.,toxicity). The prodrug can be readily prepared from the inventivecompounds using methods known in the art, such as those described byBurger's Medicinal Chemistry and Drug Chemistry, Fifth Ed., Vol. 1, pp.172-178, 949-982 (1995). For example, the inventive compounds can betransformed into prodrugs by converting one or more of the hydroxy orcarboxy groups into esters.

“Pharmaceutically acceptable metabolite” refers to drugs that haveundergone a metabolic transformation. After entry into the body, mostdrugs are substrates for chemical reactions that may change theirphysical properties and biologic effects. These metabolic conversions,which usually affect the polarity of the compound, alter the way inwhich drugs are distributed in and excreted from the body. However, insome cases, metabolism of a drug is required for therapeutic effect. Forexample, anticancer drugs of the antimetabolite class must be convertedto their active forms after they have been transported into a cancercell. Since must drugs undergo metabolic transformation of some kind,the biochemical reactions that play a role in drug metabolism may benumerous and diverse. The main site of drug metabolism is the liver,although other tissues may also participate.

A feature characteristic of many of these transformations is that themetabolic products are more polar than the parent drugs, although apolar drug does sometimes yield a less polar product. Substances withhigh lipid/water partition coefficients, which pass easily acrossmembranes, also diffuse back readily from tubular urine through therenal tubular cells into the plasma. Thus, such substances tend to havea low renal clearance and a long persistence in the body. If a drug ismetabolized to a more polar compound, one with a lower partitioncoefficient, its tubular reabsorption will be greatly reduced. Moreover,the specific secretory mechanisms for anions and cations in the proximalrenal tubules and in the parenchymal liver cells operate upon highlypolar substances.

As a specific example, phenacetin (acetophenetidin) and acetanilide areboth mild analgesic and antipyretic agents, but are transformed withinthe body to a more polar and more effective metabolite,p-hydroxyacetanilid (acetaminophen), which is widely used today. When adose of acetanilid is given to a person, the successive metabolites peakand decay in the plasma sequentially. During the first hour, acetanilidis the principal plasma component. In the second hour, as the acetanilidlevel falls, the metabolite acetaminophen concentration reaches a peak.Finally, after a few hours, the principal plasma component is a furthermetabolite that is inert and can be excreted from the body. Thus, theplasma concentrations of one or more metabolites, as well as the drugitself, can be pharmacologically important.

The reactions involved in drug metabolism are often classified into twogroups, as shown in the Table I. Phase I (or functionalization)reactions generally consist of (1) oxidative and reductive reactionsthat alter and create new functional groups and (2) hydrolytic reactionsthat cleave esters and amides to release masked functional groups. Thesechanges are usually in the direction of increased polarity.

Phase II reactions are conjugation reactions in which the drug, or oftena metabolite of the drug, is coupled to an endogenous substrate, such asglucuronic acid, acetic acid, or sulfuric acid.

TABLE I Phase I Reactions (functionalization reactions): (1) Oxidationvia the hepatic microsomal P450 system: Aliphatic oxidation Aromatichydroxylation N-Dealkylation O-Dealkylation S-Dealkylation EpoxidationOxidative deamination Sulfoxide formation Desulfuration N-Oxidation andN-hydroxylation Dehalogenation (2) Oxidation via nonmicrosomalmechanisms: Alcohol and aldehyde oxidation Purine oxidation Oxidativedeamination (monoamine oxidase and diamine oxidase) (3) Reduction: Azoand nitro reduction (4) Hydrolysis: Ester and amide hydrolysis Peptidebond hydrolysis Epoxide hydration Phase II Reactions (conjugationreactions): (1) Glucuronidation (2) Acetylation (3) Mercapturic acidformation (4) Sulfate conjugation (5) N-, O-, and S-methylation (6)Trans-sulfuration

The compounds of the present invention possess one or more asymmetriccenter(s) and thus can be produced as mixtures (racemic and non-racemic)of stereoisomers, or as individual R- and S-stereoisomers. Theindividual stereoisomers may be obtained by using an optically activestarting material, by resolving a racemic or non-racemic mixture of anintermediate at some appropriate stage of synthesis, or by resolving acompound of formula I.

The term “isomers” refer to compounds having the same number and kind ofatoms, and hence, the same molecular weight, but differing in respect tothe arrangement or configuration of the atoms, “Stereoisomers” areisomers that differ only in the arrangement of atoms in space.“Enantiomers” are a pair of stereoisomers that are non-superimposablemirror images of each other. “Diastereoisomers” are stereoisomers whichare not mirror images of each other. “Racemic mixture” means a mixturecontaining equal, or roughly equal, parts of individual enantiomers. A“non-racemic mixture” is a mixture containing unequal, or substantiallyunequal, parts of individual enantiomers or stereoisomers.

Synthesis of Compounds

Many PARP inhibitors can be synthesized by known methods from startingmaterials that are known or are themselves commercially available. Theymay also be prepared by methods used to prepare corresponding compoundsin the literature. See, for example, Suto et al.,“Dihydroisoquinolinones: The Design and Synthesis of a New Series ofPotent Inhibitors of Poly(ADP-ribose) Polymerase”, Anticancer Drug Des.,6:107-17 (1991), which discloses processes for synthesizing a number ofdifferent PARP inhibitors.

The compounds of the present invention can also be readily prepared bystandard techniques of organic chemistry, using the general syntheticpathway depicted below. Precursor compounds can be prepared by methodsknown in the art.

A compound of formula I may be prepared by contacting an intermediate offormula II:

with NH₂R², wherein Y, R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are as definedabove for formula I.

The intermediate of formula II can be purchased from commercial sourcesor is known in the literature and accessible by processes known to thoseskilled in the art.

The above reaction involves the introduction of ammonia or alkylamino toan intermediate of formula II (a widely available and typical embodimentof which is generically substituted 1,8-naphthalic anhydride). Thereaction takes place at varying temperatures depending, for example,upon the solvent used, the solubility of the intermediates of formulasII in the solvent being used, and the susceptibility of the reaction tooxidize or participate in side reactions. Preferably, however, the abovereaction takes place in the presence of ethanol, in which case it occursat a temperature of about 40° C.

The time required for the above reaction also can vary widely, dependingon much the same factors. Typically, however, the reaction takes placewithin two hours.

The product, a compound of formula I, is isolated from the reactionmixture by conventional techniques, such as by precipitating out,extraction with an immiscible solvent under appropriate pH conditions,evaporation, filtration, crystallization, or by column chromatography onsilica gel and the like. Typically, however, the product is removed byeither crystallization or column chromatography on silica gel.

Other variations and modifications of this invention using the syntheticpathways described above will be obvious to those skilled in the art.

Typically, the compounds of formula I used in the composition of theinvention will have an IC₅₀ for inhibiting poly(ADP-ribose) polymerasein vitro of 100 uM or lower, preferably 25 uM or lower, more preferably12 uM or lower and, even more preferably, 12 mM or lower.

Pharmaceutical Compositions

A further aspect of the present invention is directed to apharmaceutical composition comprising a pharmaceutically acceptablecarrier or a diluent and a therapeutically effective amount of acompound of formula I or a pharmaceutically acceptable salt, hydrate,ester, solvate, prodrug, metabolite, stereoisomer, or mixtures(hereafter, “a compound of formula I”).

The formula I compounds of the invention are useful in the manufactureof pharmaceutical formulations comprising an effective amount thereof inconjunction with or as an admixture with excipients or carriers suitablefor either enteral or parenteral application. As such, formulations ofthe present invention suitable for oral administration may be in theform of discrete units such as capsules, cachets, tablets, troche orlozenges, each containing a predetermined amount of the activeingredient; in the form of a powder or granules; in the form of asolution or a suspension in an aqueous liquid or nonaqueous liquid; orin the form of an oil-in-water emulsion or a water-in-oil emulsion. Theactive ingredient may also be in the form of a bolus, electuary, orpaste.

The composition will usually be formulated into a unit dosage form, suchas a tablet, capsule, aqueous suspension or solution. Such formulationstypically include a solid, semisolid, or liquid carrier. Exemplarycarriers include lactose, dextrose, sucrose, sorbitol, mannitol,starches, gum acacia, calcium phosphate, mineral oil, cocoa butter, oilof theobroma, alginates, tragacanth, gelatin, syrup, methyl cellulose,polyoxyethylene sorbitan monolaurate, methyl hydroxybenzoate, propylhydroxybenzoate, talc, magnesium stearate, cornstarch and the like.

Particularly preferred formulations include tablets and gelatin capsulescomprising the active ingredient together with (a) diluents, such aslactose, dextrose, sucrose, mannitol, sorbitol, cellulose, dried cornstarch, and glycine; and/or (b) lubricants, such as silica, talcum,stearic acid, its magnesium or calcium salt, and polyethylene glycol.

Tablets may also contain binders, such as magnesium aluminum silicate,starch paste, gelatin, tragacanth, methylcellulose, sodiumcarboxymethylcellulose and polyvinylpyrrolidone; disintegrants, such asstarches, agar, alginic acid or its sodium salt, and effervescentmixtures; and/or absorbents, colorants, flavors, and sweeteners. Thecompositions of the invention may be sterilized and/or containadjuvants, such as preserving, stabilizing, swelling or emulsifyingagents, solution promoters, salts for regulating osmotic pressure,and/or buffers. In addition, the composition may also contain othertherapeutically valuable substances. Aqueous suspensions may containemulsifying and suspending agents combined with the active ingredient.All oral dosage forms may further contain sweetening and/or flavoringand/or coloring agents.

These compositions are prepared according to conventional mixing,granulating, or coating methods, respectively, and contain about 0.1 to75% of the active ingredient, preferably about 1 to 50% of the same. Atablet may be made by compressing or molding the active ingredientoptionally with one or more accessory ingredients. Compressed tabletsmay be prepared by compressing, in a suitable machine, the activeingredient in a free-flowing form such as a powder or granules,optionally mixed with a binder, lubricant, inert diluent, surfaceactive, or dispersing agent. Molded tablets may be made by molding, in asuitable machine, a mixture of the powdered active ingredient and asuitable carrier moistened with an inert liquid diluent.

When administered parenterally, the composition will normally be in aunit dosage, sterile injectable form (aqueous isotonic solution,suspension or emulsion) with a pharmaceutically acceptable carrier. Suchcarriers are preferably non-toxic, parenterally-acceptable and containnon-therapeutic diluents or solvents. Examples of such carriers includewater; aqueous solutions, such as saline (isotonic sodium chloridesolution), Ringer's solution, dextrose solution, and Hanks' solution;and nonaqueous carriers, such as 1,3-butanediol, fixed oils (e.g., corn,cottonseed, peanut, sesame oil, and synthetic mono- or di-glyceride),ethyl oleate, and isopropyl myristate.

Oleaginous suspensions can be formulated according to techniques knownin the art using suitable dispersing or wetting agents and suspendingagents. Among the acceptable solvents or suspending mediums are sterilefixed oils. For this purpose, any bland fixed oil may be used. Fattyacids, such as oleic acid and its glyceride derivatives, including oliveoil and castor oil, especially in their polyoxyethylated forms, are alsouseful in the preparation of injectables.

These oil solutions or suspensions may also contain long-chain alcoholdiluents or dispersants.

Sterile saline is a preferred carrier, and the compounds are oftensufficiently water soluble to be made up as a solution for allforeseeable needs. The carrier may contain minor amounts of additives,such as substances that enhance solubility, isotonicity, and chemicalstability, e.g., anti-oxidants, buffers and preservatives.

When administered rectally, the composition will usually be formulatedinto a unit dosage form such as a suppository or cachet. Thesecompositions can be prepared by mixing the compound with suitablenon-irritating excipients that are solid at room temperature, but liquidat rectal temperature, such that they will melt in the rectum to releasethe compound. Common excipients include cocoa butter, beeswax andpolyethylene glycols or other fatty emulsions or suspensions.

Moreover, the compounds may be administered topically, especially whenthe conditions addressed for treatment involve areas or organs readilyaccessible by topical application, including neurological disorders ofthe eye., the skin or the lower intestinal tract.

For topical application to the eye, or ophthalmic use, the compounds canbe formulated as micronized suspensions in isotonic, pH-adjusted sterilesaline or, preferably, as a solution in isotonic, pH-adjusted sterilesaline, either with or without a preservative such as benzylalkoniumchloride. Alternatively, the compounds may be formulated into ointments,such as petrolatum.

For topical application to the skin, the compounds can be formulatedinto suitable ointments containing the compounds suspended or dissolvedin, for example, mixtures with one or more of the following: mineraloil, liquid petrolatum, white petrolatum, propylene glycol,polyoxyethylene compound, polyoxypropylene compound, emulsifying wax andwater.

Alternatively, the compounds can be formulated into suitable lotions orcreams containing the active compound suspended or dissolved in, forexample, a mixture of one or more of the following: mineral oil,sorbitan monostearate, polysorbate 60, cetyl ester wax, cetearylalcohol, 2-octyldodecanol, benzyl alcohol and water.

Topical application to the lower intestinal tract can be effected inrectal suppository formulations (see above) or in suitable enemaformulations.

Formulations suitable for nasal or buccal administration, (such asself-propelling powder dispensing formulations), may comprise about 0.1%to about 5% w/w of the active ingredient or, for example, about 1% w/wof the same. In addition, some formulations can be compounded into asublingual troche or lozenge.

The formulations may conveniently be presented in unit dosage form andmay be prepared by any of the methods well known in the art of pharmacy.All methods include the step of bringing the active ingredient intoassociation with the carrier which constitutes one or more accessoryingredients. In general, the formulations are prepared by uniformly andintimately bringing the active ingredient into association with a liquidcarrier or a finely divided solid carrier or both, and then, ifnecessary, shaping the product into the desired formulation.

In a preferred embodiment, the carrier is a solid biodegradable polymeror mixture of biodegradable polymers with appropriate time releasecharacteristics and release kinetics. The composition of the inventionmay then be molded into a solid implant suitable for providingefficacious concentrations of the compounds of the invention over aprolonged period of time without the need for frequent redosing. Thecomposition of the present invention can be incorporated into thebiodegradable polymer or polymer mixture in any suitable manner known toone of ordinary skill in the art and may form a homogeneous matrix withthe biodegradable polymer, or may be encapsulated in some way within thepolymer, or may be molded into a solid implant. In one embodiment, thebiodegradable polymer or polymer mixture is used to form a soft “depot”containing the pharmaceutical composition of the present invention thatcan be administered as a flowable liquid, for example, by injection, butwhich remains sufficiently viscous to maintain the pharmaceuticalcomposition within the localized area around the injection site. Thedegradation time of the depot so formed can be varied from several daysto a few years, depending upon the polymer selected and its molecularweight. By using a polymer composition in injectable form, even the needto make an incision may be eliminated. In any event, a flexible orflowable delivery “depot” will adjust to the shape of the space itoccupies with the body with a minimum of trauma to surrounding tissues.The pharmaceutical composition of the present invention is used inamounts that are therapeutically effective and the amounts used maydepend upon the desired release profile, the concentration of thepharmaceutical composition required for the sensitizing effect, and thelength of time that the pharmaceutical composition has to be releasedfor treatment.

The composition of the invention is preferably administered as a capsuleor tablet containing a single or divided dose of the compound, or as asterile solution, suspension, or emulsion, for parenteral administrationin a single or divided dose.

In another preferred embodiment, the compounds of the invention can beprepared in lyophilized form. In this case, 1 to 100 mg of a PARPinhibitor may be lyophilized in individual vials, together with acarrier and a buffer, such as mannitol and sodium phosphate. Thecomposition may then be reconstituted in the vials with bacteriostaticwater before administration.

The compounds of the invention are used in the composition in amountsthat are therapeutically effective. While the effective amount of thePARP inhibitor will depend upon the particular compound being used,amounts of these compounds varying from about 1% to about 65% have beeneasily incorporated into liquid or solid carrier delivery systems.

Compositions and Methods for Effecting Neuronal Activity

Preferably, according to the invention, an effective therapeutic amountof the compounds and compositions described above are administered toanimals to effect a neuronal activity, preferably one that is notmediated by NMDA neurotoxicity. Such neuronal activity may consist ofstimulation of damaged neurons, promotion of neuronal regeneration,prevention of neurodegeneration and treatment of a neurologicaldisorder. Accordingly, the present invention further relates to a methodof effecting a neuronal activity in an animal, comprising administeringan effective amount of the compound of formula I to said animal.Further, the compounds of the invention inhibit PARP activity and, thus,are believed to be useful for treating neural tissue damage,particularly damage resulting from cerebral ischemia and reperfusioninjury or neurodegenerative diseases in mammals.

The term “nervous tissue” refers to the various components that make upthe nervous system including, without limitation, neurons, neuralsupport cells, glia, Schwann cells, vasculature contained within andsupplying these structures, the central nervous system, the brain, thebrain stem, the spinal cord, the junction of the central nervous systemwith the peripheral nervous system, the peripheral nervous system, andallied structures.

The term “ischemia” refers to localized tissue anemia due to obstructionof the inflow of arterial blood. Global ischemia occurs when blood flowto the entire brain ceases for a period of time. Global ischemia mayresult from cardiac arrest. Focal ischemia occurs when a portion of thebrain is deprived of its normal blood supply. Focal ischemia may resultfrom thromboembolytic occlusion of a cerebral vessel, traumatic headinjury, edema or brain tumor. Even if transient, both global and focalischemia can cause widespread neuronal damage. Although nerve tissuedamage occurs over hours or even days following the onset of ischemia,some permanent nerve tissue damage may develop in the initial minutesfollowing the cessation of blood flow to the brain. Much of this damagehas been attributed to glutamate toxicity and to the secondaryconsequences of tissue reperfusion, such as the release of vasoactiveproducts by damaged endothelium and the release of cytotoxic products,such as free radicals and leukotrines, by the damaged tissue. Ischemiacan also occur in the heart in myocardial infarction and othercardiovascular disorders in which the coronary arteries have beenobstructed as a result of atherosclerosis, thrombi, or spasm.

The term “neural tissue damage resulting from ischemia and reperfusioninjury and neurodegenerative diseases” includes neurotoxicity, such asseen in vascular stroke and global and focal ischemia. The term“neurodegenerative diseases” includes Alzheimer's disease, Parkinson'sdisease and Huntington's disease.

The term “nervous insult” refers to any damage to nervous tissue and anydisability or death resulting therefrom. The cause of nervous insult maybe metabolic, toxic, neurotoxic, iatrogenic, thermal or chemical, andincludes without limitation, ischemia, hypoxia, cerebrovascularaccident, trauma, surgery, pressure, mass effect, hemmorrhage,radiation, vasospasm, neurodegenerative disease, infection, Parkinson'sdisease, amyotrophic lateral sclerosis (ALS), myelination/demyelinationprocess, epilepsy, cognitive disorder, glutamate abnormality andsecondary effects thereof.

Examples of neurological disorders that are treatable by the method ofusing the present invention include, without limitation, trigeminalneuralgia; glossopharyngeal neuralgia; Bell's Palsy; myasthenia gravis;muscular dystrophy; amyotrophic lateral sclerosis; progressive muscularatrophy; progressive bulbar inherited muscular atrophy; herniated,ruptured or prolapsed invertebrate disk syndromes; cervical spondylosis;plexus disorders; thoracic outlet destruction syndromes; peripheralneuropathies such as those caused by lead, dapsone, ticks, porphyria, orGuillain-Barre syndrome; Alzheimer's disease; Huntington's Disease andParkinson's disease.

The method of the present invention is particularly useful for treatinga neurological disorder selected from the group consisting of:peripheral neuropathy caused by physical injury or disease state; headtrauma, such as traumatic brain injury; physical damage to the spinalcord; stroke associated with brain damage, such as vascular strokeassociated with hypoxia and brain damage, focal cerebral ischemia,global cerebral ischemia, and cerebral reperfusion injury; demyelinatingdiseases, such as multiple sclerosis; and neurological disorders relatedto neurodegeneration, such as Alzheimer's Disease, Parkinson's Disease,Huntington's Disease and amyotrophic lateral sclerosis (ALS).

The term “neuroprotective” refers to the effect of reducing, arrestingor ameliorating nervous insult, and protecting, resuscitating, orreviving nervous tissue that has suffered nervous insult.

The term “preventing neurodegeneration” includes the ability to preventneurodegeneration in patients diagnosed as having a neurodegenerativedisease or who are at risk of developing a neurodegenerative disease.The term also encompasses preventing further neurodegeneration inpatients who are already suffering from or have symptoms of aneurodegenerative disease.

The term “treating” refers to:

(i) preventing a disease, disorder or condition from occurring in ananimal that may be predisposed to the disease, disorder and/orcondition, but has not yet been diagnosed as having it;

(ii) inhibiting the disease, disorder or condition, i.e., arresting itsdevelopment; and

(iii) relieving the disease, disorder or condition, i.e., causingregression of the disease, disorder and/or condition.

Treating Other PARP-Related Disorders

The compounds, compositions and methods of the present invention areparticularly useful for treating or preventing tissue damage resultingfrom cell death or damage due to necrosis or apoptosis.

The compounds, compositions and methods of the invention can also beused to treat a cardiovascular disorder in an animal, by administeringan effective amount of the compound of formula to the animal.

As used herein, the term “cardiovascular disorders” refers to thosedisorders that can either cause ischemia or are caused by reperfusion ofthe heart. Examples include, but are not limited to, coronary arterydisease, angina pectoris, myocardial infarction, cardiovascular tissuedamage caused by cardiac arrest, cardiovascular tissue damage caused bycardiac bypass, cardiogenic shock, and related conditions that would beknown by those of ordinary skill in the art or which involve dysfunctionof or tissue damage to the heart or vasculature, especially, but notlimited to, tissue damage related to PARP activation.

For example, the methods of the invention are believed to be useful fortreating cardiac tissue damage, particularly damage resulting fromcardiac ischemia or caused by reperfusion injury in animals. The methodsof the invention are particularly useful for treating cardiovasculardisorders selected from the group consisting of: coronary arterydisease, such as atherosclerosis; angina pectoris; myocardialinfarction; myocardial ischemia and cardiac arrest; cardiac bypass; andcardiogenic shock. The methods of the invention are particularly helpfulin treating the acute forms of the above cardiovascular disorders.

Further, the methods of the invention can be used to treat tissue damageresulting from cell damage or death due to necrosis or apoptosis, neuraltissue damage resulting from ischemia and reperfusion injury,neurological disorders and neurodegenerative diseases; to prevent ortreat vascular stroke; to treat or prevent cardiovascular disorders; totreat other conditions and/or disorders such as age-related maculardegeneration, AIDS and other immune senescence diseases, arthritis,atherosclerosis, cachexia, cancer, degenerative diseases of skeletalmuscle involving replicative senescence, diabetes, head trauma, immunesenescence, inflammatory bowel disorders (such as colitis and Crohn'sdisease), muscular dystrophy, osteoarthritis, osteoporosis, chronicand/or acute pain (such as neuropathic pain), renal failure, retinalischemia, septic shock (such as endotoxic shock), and skin aging; toextend the lifespan and proliferative capacity of cells; to alter geneexpression of senescent cells; or to radiosensitize tumor cells

Further still, the methods of the invention can be used to treat cancerand to radiosensitize tumor cells. The term “cancer” is interpretedbroadly. The compounds of the present invention can be “anti-canceragents”, which term also encompasses “anti-tumor cell growth agents” and“anti-neoplastic agents”. For example, the methods of the invention areuseful for treating cancers and radiosensitizing tumor cells in cancerssuch as ACTH-producing tumors, acute lymphocytic leukemia, acutenonlymphocytic leukemia, cancer of the adrenal cortex, bladder cancer,brain cancer, breast cancer, cervical cancer, chronic lymphocyticleukemia, chronic myelocytic leukemia, colorectal cancer, cutaneousT-cell lymphoma, endometrial cancer, esophageal cancer, Ewing's sarcoma,gallbladder cancer, hairy cell leukemia, head & neck cancer, Hodgkin'slymphoma, Kaposi's sarcoma, kidney cancer, liver cancer, lung cancer(small and/or non-small cell), malignant peritoneal effusion, malignantpleural effusion, melanoma, mesothelioma, multiple myeloma,neuroblastoma, non-Hodgkin's lymphoma, osteosarcoma, ovarian cancer,ovary (germ cell) cancer, prostate cancer, pancreatic cancer, penilecancer, retinoblastoma, skin cancer, soft-tissue sarcoma, squamous cellcarcinomas, stomach cancer, testicular cancer, thyroid cancer,trophoblastic neoplasms, uterine cancer, vaginal cancer, cancer of thevulva and Wilm's tumor.

The term “radiosensitizer”, as used herein, is defined as a molecule,preferably a low molecular weight molecule, administered to animals intherapeutically effective amounts to increase the sensitivity of thecells to be radiosensitized to electromagnetic radiation and/or topromote the treatment of diseases which are treatable withelectromagnetic radiation. Diseases which are treatable withelectromagnetic radiation include neoplastic diseases, benign andmalignant tumors, and cancerous cells. Electromagnetic radiationtreatment of other diseases not listed herein are also contemplated bythe present invention. The terms “electromagnetic radiation” and“radiation” as used herein includes, but is not limited to, radiationhaving the wavelength of 10⁻²⁰ to 10⁰ meters. Preferred embodiments ofthe present invention employ the electromagnetic radiation of:gamma-radiation (10⁻²⁰ to 10⁻¹³ m) x-ray radiation (10⁻¹¹ to 10⁻⁹ m),ultraviolet light (10 nm to 400 nm), visible light (400 nm to 700 nm),infrared radiation (700 nm to 1.0 mm), and microwave radiation (1 mm to30 cm).

Radiosensitizers are known to increase the sensitivity of cancerouscells to the toxic effects of electromagnetic radiation. Severalmechanisms for the mode of action of radiosensitizers have beensuggested in the literature including: hypoxic cell radiosensitizers(e.g., 2-nitroimidazole compounds, and benzotriazine dioxide compounds)promote the reoxygenation of hypoxic tissue and/or catalyze thegeneration of damaging oxygen radicals; non-hypoxic cellradiosensitizers (e.g., halogenated pyrimidines) can be analogs of DNAbases and preferentially incorporate into the DNA of cancer cells andthereby promote the radiation-induced breaking of DNA molecules and/orprevent the normal DNA repair mechanisms; and various other potentialmechanisms of action have been hypothesized for radiosensitizers in thetreatment of disease.

Many cancer treatment protocols currently employ radiosensitizersactivated by the electromagnetic radiation of x-rays. Examples of x-rayactivated radiosensitizers include, but are not limited to, thefollowing: metronidazole, misonidazole, desmethylmisonidazole,pimonidazole, etanidazole, nimorazole, mitomycin C, RSU 1069, SR 4233,EO9, RB 6145, nicotinamide, 5-bromodeoxyuridine (BUdR),5-iododeoxyuridine (IUdR), bromodeoxycytidine, fluorodeoxyuridine(FudR), hydroxyurea, cisplatin, and therapeutically effective analogsand derivatives of the same.

Photodynamic therapy (PDT) of cancers employs visible light as theradiation activator of the sensitizing agent. Examples of photodynamicradiosensitizers include the following, but are not limited to:hematoporphyrin derivatives, Photofrin, benzoporphyrin derivatives,NPe6, tin etioporphyrin SnET2, pheoborbide-a, bacteriochlorophyll-a,naphthalocyanines, phthalocyanines, zinc phthalocyanine, andtherapeutically effective analogs and derivatives of the same.

Radiosensitizers may be administered in conjunction with atherapeutically effective amount of one or more other compounds,including but not limited to: compounds which promote the incorporationof radiosensitizers to the target cells; compounds which control theflow of therapeutics, nutrients, and/or oxygen to the target cells;chemotherapeutic agents which act on the tumor with or withoutadditional radiation; or other therapeutically effective compounds fortreating cancer or other disease. Examples of additional therapeuticagents that may be used in conjunction with radiosensitizers include,but are not limited to: 5-fluorouracil, leucovorin,5′-amino-5′deoxythymidine, oxygen, carbogen, red cell transfusions,perfluorocarbons (e.g., Fluosol-DA), 2,3-DPG, BW12C, calcium channelblockers, pentoxyfylline, antiangiogenesis compounds, hydralazine, andL-BSO. Examples of chemotherapeutic agents that may be used inconjunction with radiosensitizers include, but are not limited to:adriamycin, camptothecin, carboplatin, cisplatin, daunorubicin,docetaxel, doxorubicin, interferon (alpha, beta, gamma), interleukin 2,irinotecan, paclitaxel, topotecan, and therapeutically effective analogsand derivatives of the same.

The compounds of the present invention may also be used forradiosensitizing tumor cells.

The term “treating” refers to:

(i) preventing a disease, disorder or condition from occurring in ananimal that may be predisposed to the disease, disorder and/orcondition, but has not yet been diagnosed as having it;

(ii) inhibiting the disease, disorder or condition, i.e., arresting itsdevelopment; and

(iii) relieving the disease, disorder or condition, i.e., causingregression of the disease, disorder and/or condition.

Administration

For medical use, the amount required of a compound of formula I toachieve a therapeutic effect will vary according to the particularcompound administered, the route of administration, the mammal undertreatment, and the particular disorder or disease concerned. A suitablesystemic dose of a compound of formula I for a mammal suffering from, orlikely to suffer from, any condition as described herein is typically inthe range of about 0.1 to about 100 mg of base per kilogram of bodyweight, preferably from about 1 to about 10 mg/kg of mammal body weight.It is understood that the ordinarily skilled physician or veterinarianwill readily be able to determine and prescribe the amount of thecompound effective for the desired prophylactic or therapeutictreatment.

In so proceeding, the physician or veterinarian may employ anintravenous bolus followed by an intravenous infusion and repeatedadministrations, as considered appropriate. In the methods of thepresent invention, the compounds may be administered, for example,orally, parenterally, by inhalation spray, topically, rectally, nasally,buccally, sublingually, vaginally, intraventricularly, or via animplanted reservoir in dosage formulations containing conventionalnon-toxic pharmaceutically-acceptable carriers, adjuvants and vehicles.

Parenteral includes, but is not limited to, the following examples ofadministration: intravenous, subcutaneous, intramuscular, intraspinal,intraosseous, intraperitoneal, intrathecal, intraventricular,intrasternal or intracranial injection and infusion techniques, such asby subdural pump. Invasive techniques are preferred, particularly directadministration to damaged neuronal tissue. While it is possible for thecompound of formula I to be administered alone, it is preferable toprovide it as a part of a pharmaceutical formulation.

To be effective therapeutically as central nervous system targets, thecompounds used in the methods of the present invention should readilypenetrate the blood-brain barrier when peripherally administered.Compounds which cannot penetrate the blood-brain barrier, however, canstill be effectively administered by an intraventricular route.

The compounds used in the methods of the present invention may beadministered by a single dose, multiple discrete doses or continuousinfusion. Since the compounds are small, easily diffusible andrelatively stable, they are well suited to continuous infusion. Pumpmeans, particularly subcutaneous or subdural pump means, are preferredfor continuous infusion.

For the methods of the present invention, any effective administrationregimen regulating the timing and sequence of doses may be used. Dosesof the compounds preferably include pharmaceutical dosage unitscomprising an efficacious quantity of active compound. By an efficaciousquantity is meant a quantity sufficient to inhibit PARP activity and/orderive the desired beneficial effects therefrom through administrationof one or more of the pharmaceutical dosage units. In a particularlypreferred embodiment, the dose is sufficient to prevent or reduce theeffects of vascular stroke or other neurodegenerative diseases.

An exemplary daily dosage unit for a vertebrate host comprises an amountof from about 0.001 mg/kg to about 50 mg/kg. Typically, dosage levels onthe order of about 0.1 mg to about 10,000 mg of the active ingredientcompound are useful in the treatment of the above conditions, withpreferred levels being about 0.1 mg to about 1,000 mg. The specific doselevel for any particular patient will vary depending upon a variety offactors, including the activity of the specific compound employed; theage, body weight, general health, sex, and diet of the patient; the timeof administration; the rate of excretion; any combination of thecompound with other drugs; the severity of the particular disease beingtreated; and the form and route of administration. Typically, in vitrodosage-effect results provide useful guidance on the proper doses forpatient administration. Studies in animal models can also be helpful.The considerations for determining the proper dose levels are well-knownin the art.

In methods of treating nervous insult (particularly acute ischemicstroke and global ischemia caused by drowning or head trauma), thecompounds of the invention can be co-administered with one or more othertherapeutic agents, preferably agents which can reduce the risk ofstroke (such as aspirin) and, more preferably, agents which can reducethe risk of a second ischemic event (such as ticlopidine).

The compounds and compositions can be co-administered with one or moretherapeutic agents either (i) together in a single formulation, or (ii)separately in individual formulations designed for optimal release ratesof their respective active agent. Each formulation may contain fromabout 0.01% to about 99.99% by weight, preferably from about 3.5% toabout 60% by weight, of the compound of the invention, as well as one ormore pharmaceutical excipients, such as wetting, emulsifying and pHbuffering agents. When the compounds used in the methods of theinvention are administered in combination with one or more othertherapeutic agents, specific dose levels for those agents will dependupon considerations such as those identified above for compositions andmethods of the invention in general.

For example, Table II below provides known median dosages for selectedchemotherapeutic agents that may be administered in combination with thecompounds of the invention to such diseases or various cancers.

TABLE II CHEMOTHERAPEUTIC AGENT MEDIAN DOSAGE Asparaginase 10,000 unitsBleomycin Sulfate 15 units Carboplatin 50-450 mg Carmustine 100 mgCisplatin 10-50 mg Cladribine 10 mg Cyclophosphamide (lyophilized) 100mg to 2 gm Cyclophosphamide (non-lyophilized) 100 mg to 2 gm Cytarabine(lyophilized powder) 100 mg to 2 gm Dacarbazine 100-200 mg Dactinomycin0.5 mg Daunorubicin 20 mg Diethylstilbestrol 250 mg Doxorubicin 10-150mg Etidronate 300 mg Etoposide 100 mg Floxuridine 500 mg FludarabinePhosphate 50 mg Fluorouracil 500 mg to 5 gm Goserelin 3.6 mg GranisetronHydrochloride 1 mg Idarubicin 5-10 mg Ifosfamide 1-3 gm LeucovorinCalcium 50-350 mg Leuprolide 3.75-7.5 mg Mechlorethamine 10 mgMedroxyprogesterone 1 gm Melphalan 50 gm Methotrexate 20 mg to 1 gmMitomycin 5-40 mg Mitoxantrone 20-30 mg Ondansetron Hydrochloride 40 mgPaclitaxel 30 mg Pamidronate Disodium 30-90 mg Pegaspargase 750 unitsPlicamycin 2,500 mcgm Streptozocin 1 gm Thiotepa 15 mg Teniposide 50 mgVinblastine 10 mg Vincristine 1-5 mg Aldesleukin 22 million unitsEpoetin Alfa 2,000-10,000 units Filgrastim 300-480 mcgm Immune Globulin500 mg to 10 gm Interferon Alpha-2a 3-36 million units InterferonAlpha-2b 3-50 million units Levamisole 50 mg Octreotide 1,000-5,000 mcgmSargramostim 250-500 mcgm

For the methods of the present invention, any administration regimenregulating the timing and sequence of delivery of the compound can beused and repeated as necessary to effect treatment. Such regimen mayinclude pretreatment and/or co-administration with additionaltherapeutic agents.

To maximize protection of nervous tissue from nervous insult, thecompounds of the invention should be administered to the affected cellsas soon as possible. In situations where nervous insult is anticipated,the compounds are advantageously administered before the expectednervous insult. Such situations of increased likelihood of nervousinsult include surgery, such as carotid endarterectomy, cardiac,vascular, aortic, orthopedic surgery; endovascular procedures, such asarterial catheterization (carotid, vertebral, aortic, cardia, renal,spinal, Adamkiewicz); injections of embolic agents; the use of coils orballoons for hemostasis; interruptions of vascularity for treatment ofbrain lesions; and predisposing medical conditions such as crescendotransient ischemic attacks, emboli and sequential strokes.

Where pre-treatment for stroke or ischemia is impossible orimpracticable, it is important to bring the compounds of the inventioninto contact with the affected cells as soon as possible, either duringor after the event. In the time period between strokes, however,diagnosis and treatment procedures should be minimized to save the cellsfrom further damage and death. Therefore, a particularly advantageousmode of administration with a patient diagnosed with acute multiplevascular strokes is by implantation of a subdural pump to deliver thecompound(s) of the invention directly to the infarct area of the brain.Even if comatose, it is expected that the patient would recover morequickly that he or she would without this treatment. Moreover, in anyconscious state of the patient, it is expected that any residualneurological symptoms, as well as the re-occurrence of stroke, would bereduced.

As to patients diagnosed with other acute disorders believed to berelated to PARP activity, such as diabetes, arthritis and Crohn'sdisease, the compound of the invention should also be administered assoon as possible, either in a single dose or as a series of divideddoses.

Depending on the patient's presenting symptoms and the degree ofresponse to the initial administration of the compound of the invention,the patient may further receive additional doses of the same ordifferent compounds of the invention, by one of the following routes:parenterally, such as by injection or by intravenous administration;orally, such as by capsule or tablet; by implantation of abiocompatible, biodegradable polymeric matrix delivery system comprisingthe compound; or by direct administration to the infarct area byinsertion of a subdural pump or a central line. It is expected that thetreatment would alleviate the disorder, either in part or in itsentirety and that fewer further occurrences of the disorder woulddevelop. It also is expected that the patient would suffer fewerresidual symptoms.

Where a patient is diagnosed with an acute disorder prior to theavailability of the compounds of the invention, the patient's conditionmay deteriorate due to the acute disorder and become a chronic disorderby the time that the compounds are available. Even when a patientreceives a compound of formula I for the chronic disorder, it is alsoexpected that the patient's condition would stabilize and actuallyimprove as a result of receiving the compound.

EXAMPLES

The following are illustrative of preferred embodiments of relatedinventions and are not to be construed as limiting the present inventionthereto. All polymer molecular weights are mean average molecularweights. All percentages are based on the percent by weight of the finaldelivery system or formulation prepared unless otherwise indicated, andall totals equal 100% by weight.

Example 1 Preparation of R-substituted1H-Benzo[de]iso-quinoline-1,3(2H)-diones

The starting R-substituted 1,8-naphthalic anhydride may be purchasedfrom commercial sources or may be known in the chemistry literature andaccessible by processes known to one skilled in the art. To a solutionof R-substituted 1,8-naphthalic anhydride (1) (10 mmol) in ethanol (100ml), ammonia is introduced at a temperature of 40° C. After about fiveminutes, the ammonia gas line is withdrawn and the mixture is stirredcontinuously at 50° C. for two hours. The ethanol solvent and excessammonia are removed in vacuo. The resulting residue is purified eitherby crystallization or by column chromatography on silica gel to give thedesired 1H-benzo[de]isoquinoline-1,3(2H)-dione (2), which appears asessentially colorless crystals.

Example 2 Preparation of R-substituted2,3,3a,9b-Tetrahydro-1H-benzo[de]isoquinolin-1-ones

To a solution of sodium borohydride (5 mmol) in ethanol/water (20 ml,v/v:10/1), the R-substituted 1H-benzo[de]isoquinoline-1,3(2H)-dione (0.5mmol), obtained from Example 1 above is added. The resulting mixture isstirred for four hours at 60° C. After quenching the reaction with 2Nhydrochloric acid, the reaction mixture is extracted with methylenechloride (30 ml×3). The organic layers over combined and dried overanhydrous sodium sulfate. The solvent is then removed leaving a solidresidue. The residue is purified either by crystallization or by columnchromatography on silica gel, to give the desired compound, aR-substituted 2,3,3a,9b-tetrahydro-1H-benzo[de]iso-quinolin-1-one (2),which appears as essentially colorless crystals.

Example 3 Approximate IC₅₀ Data for Selected Compounds

The IC₅₀ of with respect to PARP inhibition was determined for severalcompounds by a PARP assay using purified recombinant human PARP fromTrevigen (Gaithersburg, MD), as follows: The PARP enzyme assay was setup on ice in a volume of 100 microliters consisting of 10 mM Tris-HCl(pH 8.0), 1 mM MgCl₂, 28 mM KCl, 28 mM NaCl, 0.1 mg/ml of herring spermDNA (activated as a 1 mg/ml stock for 10 minutes in a 0.15% hydrogenperoxide solution), 3.0 micromolar [3H]nicotinamide adenine dinucleotide(470 mci/mmole), 7 micrograms/ml PARP enzyme, and various concentrationsof the compounds to be tested. The reaction was initiated by incubatingthe mixture at 25° C. After 15 minutes' incubation, the reaction wasterminated by adding 500 microliters of ice cold 20% (w/v)trichloroacetic acid. The precipitate formed was transferred onto aglass fiber filter (Packard Unifilter-GF/B) and washed three times withethanol. After the filter was dried, the radioactivity was determined byscintillation counting.

Using the PARP assay described above, approximate IC₅₀ values wereobtained for the following compounds:

Compound Approximate IC_(50′s)

0.40

0.54

0.09

4.0

0.46

2.8

0.81

Similar IC₅₀ values are obtained for the compounds of the invention.

Example 4 Neuroprotective Effect of DPQ on Focal Cerebral Ischemia inRats

Focal cerebral ischemia was produced by cauterization of the rightdistal MCA (middle cerebral artery) with bilateral temporary commoncarotid artery occlusion in male Long-Evans rats for 90 minutes. Allprocedures performed on the animals were approved by the UniversityInstitutional Animal Care and Use Committee of the University ofPennsylvania. A total of 42 rats (weights: 230-340 g) obtained fromCharles River were used in this study. The animals fasted overnight withfree access to water prior to the surgical procedure.

Two hours prior to MCA occlusion, varying amounts (control, n=14; 5mg/kg, n=7; 10 mg/kg, n=7; 20 mg/kg, n=7; and 40 mg/kg, n=7) of thecompound, 3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone(“DPQ”) were dissolved in dimethyl sulfoxide (DMSO) using a sonicator. Avolume of 1.28 ml/kg of the resulting solution was injectedintraperitoneally into fourteen rats.

The rats were then anesthetized with halothane (4% for induction and0.8%-1.2% for the surgical procedure) in a mixture of 70% nitrous oxideand 30% oxygen. The body temperature was monitored by a rectal probe andmaintained at 37.5±0.5° C. with a heating blanket regulated by ahomeothermic blanket control unit (Harvard Apparatus Limited, Kent,U.K.). A catheter (PE-50) was placed into the tail artery, and arterialpressure was continuously monitored and recorded on a Grass polygraphrecorder (Model 7D, Grass Instruments, Quincy, Mass.). Samples for bloodgas analysis (arterial pH, PaO₂ and PaCO₂) were also taken from the tailartery catheter and measured with a blood gas analyzer (ABL 30,Radiometer, Copenhagen, Denmark). Arterial blood samples were obtained30 minutes after MCA occlusion.

The head of the animal was positioned in a stereotaxic frame, and aright parietal incision between the right lateral canthus and theexternal auditory meatus was made. Using a dental drill constantlycooled with saline, a 3 mm burr hole was prepared over the cortexsupplied by the right MCA, 4 mm lateral to the sagittal suture and 5 mmcaudal to the coronal suture. The dura mater and a thin inner bone layerwere kept, care being taken to position the probe over a tissue areadevoid of large blood vessels. The flow probe (tip diameter of 1 mm,fiber separation of 0.25 mm) was lowered to the bottom of the cranialburr hole using a micromanipulator. The probe was held stationary by aprobe holder secured to the skull with dental cement. The microvascularblood flow in the right parietal cortex was continuously monitored witha laser Doppler flowmeter (FloLab, Moor, Devon, U.K., and Periflux 4001,Perimed, Stockholm, Sweden).

Focal cerebral ischemia was produced by cauterization of the distalportion of the right MCA with bilateral temporary common carotid artery(CCA) occlusion by the procedure of Chen et al., “A Model of FocalIschemic Stroke in the Rat: Reproducible Extensive Cortical Infarction”,Stroke 17:738-43 (1986) and/or Liu et al., “PolyethyleneGlycol-conjugated Superoxide Dismutase and Catalase Reduce IschemicBrain Injury”, Am. J. Physiol. 256:H589-93 (1989), both of which arehereby incorporated by reference.

Specifically, bilateral CCA's were isolated, and loops made frompolyethylene (PE-10) catheter were carefully passed around the CCA's forlater remote occlusion. The incision made previously for placement ofthe laser doppler probe was extended to allow observation of the rostralend of the zygomatic arch at the fusion point using a dental drill, andhe dura mater overlying the MCA was cut. The MCA distal to its crossingwith the inferior cerebral vein was lifted by a fine stainless steelhook attached to a micromanipulator and, following bilateral CCAocclusion, the MCA was cauterized with an electrocoagulator. The burrhole was covered with a small piece of Gelform, and the wound wassutured to maintain the brain temperature within the normal ornear-normal range.

After 90 minutes of occlusion, the carotid loops were released, the tailarterial catheter was removed, and all of the wounds were sutured.Gentamicin sulfate (10 mg/ml) was topically applied to the wounds toprevent infection. The anesthetic was discontinued, and the animal wasreturned to his cage after awakening. Water and food were allowed adlibitum.

Two hours after MCA occlusion, the animals were given the same doses ofthe PARP inhibitor as in the pre-treatment. Twenty-four hours after MCAocclusion, the rats were sacrificed with an intraperitoneal injection ofpentobarbital sodium (150 mg/kg). The brain was carefully removed fromthe skull and cooled in ice-cold artificial CSF for five minutes. Thecooled brain was then sectioned in the coronal plane at 2 mm intervalsusing a rodent brain matrix (RBM-4000C, ASI Instruments, Warren, Mich.).The brain slices were incubated in phosphate-buffered saline containing2% 2,3,5-triphenyltetrazolium chloride (TTC) at 37° C. for ten minutes.Color photographs were taken of the posterior surface of the stainedslices and were used to determine the damaged area at eachcross-sectional, level using a computer-based image analyzer (NIH Image1.59). To avoid artifacts due to edema, the damaged area was calculatedby subtracting the area of the normal tissue in the hemisphereipsilateral to the stroke from the area of the hemisphere contralateralto the stroke, by the method of Swanson et al., “A Semiautomated Methodfor Measuring Brain Infarct Volume”, J. Cereb. Blood Flow Metabol.10:290-93 (1990), the disclosure of which is hereby incorporated byreference. The total volume of infarction was calculated by summation ofthe damaged volume of the brain slices.

The cauterization of the distal portion of the right MCA with bilateraltemporary CCA occlusion consistently produced a well-recognized corticalinfarct in the right MCA territory of each test animal. There was anapparent uniformity in the distribution of the damaged area as measuredby TTC staining in each group, as shown in FIG. 1.

In FIG. 1, the distribution of the cross-sectional infarct area atrepresentative levels along the rostrocaudal axis was measured from theinteraural line in non-treated animals and in animals treated with 10mg/kg of 3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone.The area of damage was expressed as mean±standard deviation. Significantdifferences between the 10 mg-treated group and the control group wereindicated (*p<0.02, **p<0.01, **p<0.001). The 5 mg/kg and 20 mg/kgcurves fell approximately halfway between the control and the 10 mg/kgcurves, whereas the 40 mg/kg curve was close to the control. The 5, 20and 40 mg/kg curves were omitted for clarity.

PARP inhibition led to a significant decrease in the damaged volume inthe 5 mg/kg-treated group (106.7±23.2 mm³, p<0.001), the 10mg/kg-treated group (76.4±16.8 mm³, p<0.001), and the 20 mg/kg-treatedgroup (110.2±42.0 mm³, p<0.01), compared to the control group(165.2±34.0 mm³. The data are expressed as mean±standard deviation. Thesignificance of differences between groups was determined using ananalysis of variance (ANOVA) followed by Student's t-test for individualcomparisons.

There was no significant difference between the control and the 40mg/kg-treated group (135.6±44.8 mm³). However, there were significantdifferences between the 5 mg/kg-treated group and the 10 mg/kg-treatedgroup (p<0.02), and between the 10 mg/kg-treated group and the 40mg/kg-treated group (p<0.01), as shown in FIG. 2.

In FIG. 2, the effect of intraperitoneal administration of3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone on theinfarct volume was depicted graphically. The volumes of infarct wereexpressed as mean±standard deviation. Significant differences betweenthe treated groups and the control group were indicated (*p<0.01,**p<0.001). It is not clear why a high dose (40 mg/kg) of the PARPinhibitor,3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone, was lessneuroprotective. The U-shaped dose-response curve may suggest dualeffects of the compound.

However, overall, the in vivo administration of the inhibitor led to asubstantial reduction in infarct volume in the focal cerebral ischemiamodel in the rat. This result indicated that the activation of PARPplays an important role in the pathogenesis of brain damage in cerebralischemia.

The values of arterial blood gases (PaO₂, PaCO₂ and pH) were within thephysiological range in the control and treated groups with nosignificant differences in these parameters among the five groups, asshown below in Table 2. A “steady state” MABP was taken followingcompletion of the surgical preparation, just prior to occlusion; an“ischemia” MABP was taken as the average MABP during occlusion.

TABLE III MABP (mm Hg) PaO₂ PaCO₂ Steady Ischemia (mm Hg) (mm Hg) pHState Control 125 ± 21 38.6 ± 4.6 7.33 ± 0.05  79 ± 14 91 ± 13** group(n = 4) 5 mg/kg- 126 ± 20 38.0 ± 2.8 7.36 ± 0.02 78 ± 5 91 ± 12**treated group (n = 7) 10 mg/kg- 125 ± 16 39.3 ± 5.2 7.34 ± 0.03 80 ± 990 ± 14*  treated group (n = 7) 20 mg/kg- 122 ± 14 41.3 ± 2.8 7.35 ±0.23  79 ± 10 91 ± 12** treated group (n = 7) 40 mg/kg- 137 ± 17 39.5 ±4.7 7.33 ± 0.024 78 ± 4 88 ± 12*  treated group (n = 7) *= Significantlydifferent from the steady state value, p < 0.05. **= Significantlydifferent from the steady state value, p < 0.01.

There were no significant differences in any physiological parameter,including mean arterial blood pressure (MABP), prior to MCA and CCAocclusion among the five groups. Although MABP was significantlyelevated following occlusion in all five groups, there were nosignificant differences in MABP during the occlusion period among thegroups.

Since the blood flow values obtained from the laser doppler were inarbitrary units, only percent changes from the baseline (prior toocclusion) were reported. Right MCA and bilateral CCA occlusion produceda significant decrease in relative blood flow in the right parietalcortex to 20.8±7.7% of the baseline in the control group (n=5),18.7±7.4% in the 5 mg/kg-treated group (n=7), 21.4±7.7% in the 10mg/kg-treated group (n=7) and 19.3±11.2% in the 40 mg/kg-treated group(n=7). There were no significant differences in the blood flow responseto occlusion among the four groups. In addition, blood flow showed nosignificant changes throughout the entire occlusion period in any group.

Following release of the carotid occlusions, a good recovery of bloodflow (sometimes hyperemia) was observed in the right MCA territory ofall animals. Reperfusion of the ischemic tissue resulted in theformation of No and peroxynitrite, in addition to oxygen-derived freeradicals. All of these radicals have been shown to cause DNA strandbreaks and to activate PARP.

This example provided evidence that the related compounds of the presentinvention are effective in inhibiting PARP activity.

Example 5 Retinal Ischemia Protection

A patient just diagnosed with acute retinal ischemia is immediatelyadministered parenterally, either by intermittent or continuousintravenous administration, a compound of formula I, either as a singledose or a series of divided doses of the compound. After this initialtreatment, and depending on the patient's presenting neurologicalsymptoms, the patient optionally may receive the same or a differentcompound of the invention in the form of another parenteral dose. It isexpected by the inventors that significant prevention of neural tissuedamage would ensue and that the patient's neurological symptoms wouldconsiderably lessen due to the administration of the compound, leavingfewer residual neurological effects post-stroke. In addition, it isexpected that the re-occurrence of retinal ischemia would be preventedor reduced.

Example 6 Treatment of Retinal Ischemia

A patient has just been diagnosed with acute retinal ischemia.Immediately, a physician or a nurse parenterally administers a compoundof formula I, either as a single dose or as a series of divided doses.The patient also receives the same or a different PARP inhibitor byintermittent or continuous administration via implantation of abiocompatible, biodegradable polymeric matrix delivery system comprisinga compound of formula I, or via a subdural pump inserted to administerthe compound directly to the infarct area of the brain. It is expectedby the inventors that the patient would awaken from the coma morequickly than if the compound of the invention were not administered. Thetreatment is also expected to reduce the severity of the patient'sresidual neurological symptoms. In addition, it is expected thatre-occurrence of retinal ischemia would be reduced.

Example 7 Assay for Neuroprotective Effects on Focal Cerebral Ischemiain Rats

Focal cerebral ischemia experiments are performed using male Wistar ratsweighing 250-300 g, which are anesthetized with 4% halothane. Anesthesiais maintained with 1.0-1.5% halothane until the end of surgery. Theanimals are installed in a warm environment to avoid a decrease in bodytemperature during surgery.

An anterior midline cervical incision is made. The right common carotidartery (CCA) is exposed and isolated from the vagus nerve. A silk sutureis placed and tied around the CCA in proximity to the heart. Theexternal carotid artery (ECA) is then exposed and ligated with a silksuture. A puncture is made in the CCA and a small catheter (PE 10,Ulrich & Co., St-Gallen, Switzerland) is gently advanced to the lumen ofthe internal carotid artery (ICA). The pterygopalatine artery is notoccluded. The catheter is tied in place with a silk suture. Then, a 4-0nylon suture (Braun Medical, Crissier, Switzerland) is introduced intothe catheter lumen and is pushed until the tip blocks the anteriorcerebral artery. The length of catheter into the ICA is approximately 19mm from the origin of the ECA. The suture is maintained in this positionby occlusion of the catheter with heat. One cm of catheter and nylonsuture are left protruding so that the suture can be withdrawn to allowreperfusion. The skin incision is then closed with wound clips.

The animals are maintained in a warm environment during recovery fromanesthesia. Two hours later, the animals are re-anesthetized, the clipsare discarded, and the wound is re-opened. The catheter is cut, and thesuture is pulled out. The catheter is then obturated again by heat, andwound clips are placed on the wound. The animals are allowed to survivefor 24 hours with free access to food and water. The rats are thensacrificed with CO₂ and decapitated.

The brains are immediately removed, frozen on dry ice and stored at −80°C. The brains are then cut in 0.02 mm-thick sections in a cryocut at−19° C., selecting one of every 20 sections for further examination. Theselected sections are stained with cresyl violet according to the Nisslprocedure.

Each stained section is examined under a light microscope, and theregional infarct area is determined according to the presence of cellswith morphological changes.

Various doses of the compounds of the invention are tested in thismodel. The compounds are administered in either a single dose or aseries of multiple doses, i.p. or i.v., at different times, both beforeor after the onset of ischemia. Compounds of the invention are found toprovide protection from ischemia in the range of about 20 to 80%.

Example 8 Effects on Heart Ischemia/Reperfusion Injury in Rats

Female Sprague-Dawley rats, each weighing about 300-350 g areanesthetized with intraperitoneal ketamine at a dose of 150 mg/kg. Therats are endotracheally intubated and ventilated with oxygen-enrichedroom air using a Harvard rodent ventilator. Polyethylene cathetersinserted into the carotid artery and the femoral vein are used forartery blood pressure monitoring and fluid administration respectively.Arterial pCO₂ is maintained between 35 and 45 mm Hg by adjusting therespirator rate. The rat chests are opened by median sternotomy, thepericardium is incised, and the hearts are cradled with a latex membranetent. Hemodynamic data are obtained at baseline after at least a15-minute stabilization period following the end of the surgicaloperation. The LAD (left anterior descending) coronary artery is ligatedfor 40 minutes, and then re-perfused for 120 minutes. After 120 minutes'reperfusion, the LAD artery is re-occluded, and a 0.1 ml bolus ofmonastral blue dye is injected into the left atrium to determine theischemic risk region.

The hearts are then arrested with potassium chloride and cut into five2-3 mm thick transverse slices. Each slice is weighed and incubated in a1% solution of trimethyltetrazolium chloride to visualize the infarctedmyocardium located within the risk region. Infarct size is calculated bysumming the values for each left ventricular slice and is furtherexpressed as a fraction of the risk region of the left ventricle.

Various doses of the compounds of the invention are tested in thismodel. The compounds are given either in a single dose or a series ofmultiple doses, i.p. or i.v., at different times, both before or afterthe onset of ischemia. The compounds of the invention are found to haveischemia/reperfusion injury protection in the range of 10 to 40 percent.Therefore, they protect against ischemia-induced degeneration of rathippocampal neurons in vitro.

Example 9 Vascular Stroke Protection

A patient just diagnosed with acute vascular stroke is immediatelyadministered parenterally, either by intermittent or continuousintravenous administration, a compound of formula I, either as a singledose or a series of divided doses of the compound. After this initialtreatment., and depending on the patient's presenting neurologicalsymptoms, the patient optionally may receive the same or a differentcompound of the invention in the form of another parenteral dose. It isexpected by the inventors that significant prevention of neural tissuedamage would ensue and that the patient's neurological symptoms wouldconsiderably lessen due to the administration of the compound, leavingfewer residual neurological effects post-stroke. In addition, it isexpected that the re-occurrence of vascular stroke would be prevented orreduced.

Example 10 Treatment of Vascular Stroke

A patient has just been diagnosed with acute multiple vascular strokesand is comatose. Immediately, a physician or a nurse parenterallyadministers a compound of formula I, either as a single dose or as aseries of divided doses. Due to the comatose state of the patient, thepatient also receives the same or a different PARP inhibitor byintermittent or continuous administration via implantation of abiocompatible, biodegradable polymeric matrix delivery system comprisinga compound of formula I, or via a subdural pump inserted to administerthe compound directly to the infarct area of the brain. It is expectedby the inventors that the patient would awaken from the coma morequickly than if the compound of the invention were not administered. Thetreatment is also expected to reduce the severity of the patient'sresidual neurological symptoms. In addition, it is expected thatre-occurrence of vascular stroke would be reduced.

Example 11 Preventing Cardiac Reperfusion Injury

A patient is diagnosed with life-threatening cardiomyopathy and requiresa heart transplant. Until a donor heart is found, the patient ismaintained on Extra Corporeal Oxygenation Monitoring (ECMO).

A donor heart is then located, and the patient undergoes a surgicaltransplant procedure, during which the patient is placed on a heart-lungpump. The patient receives a compound of the invention intracardiacwithin a specified period of time prior to re-routing his or hercirculation from the heart-lung pump to his or her new heart, thuspreventing cardiac reperfusion injury as the new heart begins to beatindependently of the external heart-lung pump.

Example 12 Septic Shock Assay

Groups of 10 C57/BL male mice weighing 18 to 20 g were administered atest compound, 1-carboxynaphthalene-1-carboxamide at the doses of 60,20, 6 and 2 mg/kg, daily, by intraperitoneal (IP) injection for threeconsecutive days. Each animal was first challenged withlipopolysaccharide (LPS, from E. Coli, LD₁₀₀ of 20 mg/animal IV) plusgalactosamine (20 mg/animal IV). The first dose of test compound in asuitable vehicle was given 30 minutes after challenge, and the secondand third doses were given 24 hours later on day 2 and day 3respectively, with only the surviving animals receiving the second orthird dose of the test compound. Mortality was recorded every 12 hoursafter challenge for the three-day testing period.1-Carboxy-naphthalene-1-carboxamide provided a protection againstmortality from septic shock of about 40%. Based on these results, othercompounds of the invention are expected to provide a protection againstmortality exceeding about 35%.

Example 13 In vitro Radiosensitization

The human prostate cancer cell line, PC-3s, were plated in 6 well dishesand grown at monolayer cultures in RPMI1640 supplemented with 10% FCS.The cells are maintained at 37° C. in 5% CO₂ and 95% air. The cells wereexposed to a dose response (0.1 mM to 0.1 uM) of 3 different PARPinhibitors of Formula I disclosed herein prior to irradiation at onesublethal dose level. For all treatment groups, the six well plates wereexposed at room temperature in a Seifert 250 kV/15 mA irradiator with a0.5 mm Cu/l mm. Cell viability was examined by exclusion of 0.4% trypanblue. Dye exclusion was assessed visually by microscopy and viable cellnumber was calculated by subtracting the number of cells from the viablecell number and dividing by the total number of cells. Cellproliferation rates were calculated by the amount of ³H-thymidineincorporation post-irradiation. The PARP inhibitors showradiosensitization of the cells.

Example 14 In vivo Radiosensitization

Before undergoing radiation therapy to treat cancer, a patient isadministered an effective amount of a compound or a pharmaceuticalcomposition of the present invention. The compound or pharmaceuticalcomposition acts as a radiosensitizer and making the tumor moresusceptible to radiation therapy.

Example 15 Measuring Altered Gene Expression in mRNA Senescent Cells

Human fibroblast BJ cells, at Population Doubling (PDL) 94, are platedin regular growth medium and then changed to low serum medium to reflectphysiological conditions described in Linskens, et al., Nucleic AcidsRes. 23:16:3244-3251 (1995). A medium of DMEM/199 supplemented with 0.5%bovine calf serum is used. The cells are treated daily for 13 days withthe PARP inhibitor of Formula I as disclosed herein. The control cellsare treated with and without the solvent used to administer the PARPinhibitor. The untreated old and young control cells are tested forcomparison. RNA is prepared from the treated and control cells accordingto the techniques described in PCT Publication No. 96/13610 and Northernblotting is conducted. Probes specific for senescence-related genes areanalyzed, and treated and control cells compared. In analyzing theresults, the lowest level of gene expression is arbitrarily set at 1 toprovide a basis for comparison. Three genes particularly relevant toage-related changes in the skin are collagen, collagenase and elastin.West, Arch. Derm. 130:87-95 (1994). Elastin expression of the cellstreated with the PARP inhibitor of Formula I is significantly increasedin comparison with the control cells. Elastin expression issignificantly higher in young cells compared to senescent cells, andthus treatment with the PARP inhibitor of Formula I causes elastinexpression levels in senescent cells to change to levels similar tothose found in much younger cells. Similarly, a beneficial effect isseen in collagenase and collagen expression with treatment with the PARPinhibitors of Formula I.

Example 16 Measuring Altered Gene Expression Protein in Senescent Cells

Approximately 105 BJ cells, at PDL 95-100 are plated and grown in 15 cmdishes. The growth medium is DMEM/199 supplemented with 10% bovice calfserum. The cells are treated daily for 24 hours with the PARP inhibitorsof Formula I (100 ug/ 1 mL of medium). The cells are washed withphosphate buffered solution (PBS), then permeablized with 4%paraformaldehyde for 5 minutes, then washed with PBS, and treated with100% cold methanol for 10 minutes. The methanol is removed and the cellsare washed with PBS, and then treated with 10% serum to blocknonspecific antibody binding. About 1 mL of the appropriate commerciallyavailable antibody solutions (1:500 dilution. Vector) is added to thecells and the mixture incubated for 1 hour. The cells are rinsed andwashed three times with PBS. A secondary antibody, goat anti-mouse IgG(1 mL) with a biotin tag is added along with 1 mL of a solutioncontaining streptavidin conjugated to alkaline phosphatase and 1 mL ofNBT reagent (Vector). The cells are washed and changes in geneexpression are noted calorimetrically. Four senescence-specificgenes—collagen I, collagen III, collagenase, and interferon gamma—insenescent cells treated with the PARP inhibitor of Formula I aremonitored and the results show a decrease in interferon gamma expressionwith no observable change in the expression levels of the other threegens, demonstrating that the PARP inhibitors of Formula I can altersenescence-specific gene expression.

Example 17 Extending or Increasing Proliferative Capacity and Lifespanof Cells

To demonstrate the effectiveness of the present method for extending theproliferative capacity and lifespan of cells, human fibroblast cellslines (either W138 at Population Doubling (PDL) 23 or BJ cells at PDL71) are thawed and plated on T75 flasks and allowed to grow in normalmedium (DMEM/M199 plus 10% bovine calf serum) for about a week, at whichtime the cells are confluent, and the cultures are therefor ready to besubdivided. At the time of subdivision, the media is aspirated, and thecells rinsed with phosphate buffer saline (PBS) and then trypsinized.The cells are counted with a Coulter counter and plated at a density of10⁵ cells per cm² in 6-well tissue culture plates in DMEM/199 mediumsupplemented with 10% bovine calf serum and varying amounts (0.10 uM,and 1 mM: from a 100× stock solution in DMEM/M199 medium) of a PARPinhibitor of Formula I as disclosed herein. This process is repeatedevery 7 days until the cell appear to stop dividing. The untreated(control) cells reach senescence and stop dividing after about 40 daysin culture. Treatment of cells with 10 uM 3-AB appears to have little orno effect in contrast to treatment with 100 uM 3-AB which appearslengthen the lifespan of the cells and treatment with 1 mM 3-AB whichdramatically increases the lifespan and proliferative capacity of thecells. The cells treated with 1 mM 3-AB will still divide after 60 daysin culture.

Example 18 Neuroprotective Effects of Formula I on Chronic ConstrictionInjury (CCI) in Rats

Adult male Sprague-Dawley rats, 300-350 g, are anesthetized withintraperitoneal 50 mg/kg sodium pentobarbital. Nerve ligation isperformed by exposing one side of the rat's sciatic nerves anddissecting a 5-7 mm-long nerve segment and closing with four looseligatures at a 1.0-1.5-mm, followed by implanting of an intrathecalcatheter and inserting of a gentamicin sulfate-flushed polyethylene(PE-10) tube into the subarachnoid space through an incision at thecisterna magna. The caudal end of the catheter is gently threaded to thelumbar enlargement and the rostral end is secured with dental cement toa screw embedded in the skull and the skin wound is closed with woundclips.

Thermal hyperalgesia to radiant heat is assessed by using apaw-withdrawal test. The rat is placed in a plastic cylinder on a 3-mmthick glass plate with a radiant heat source from a projection bulbplaced directly under the plantar surface of the rat's hindpaw. Thepaw-withdrawal latency is defined as the time elapsed from the onset ofradiant heat stimulation to withdrawal of the rat's hindpaw.

Mechanical hyperalgesia is assessed by placing the rat in a cage with abottom made of perforated metal sheet with many small square holes.Duration of paw-withdrawal is recorded after pricking the mid-plantarsurface of the rat's hindpaw with the tip of a safety pin insertedthrough the cage bottom.

Mechano-allodynia is assessed by placing a rat in a cage similar to theprevious test, and applying von Frey filaments in ascending order ofbending force ranging from 0.07 to 76 g to the mid-plantar surface ofthe rat's hindpaw. A von Frey filament is applied perpendicular to theskin and depressed slowly until it bends. A threshold force of responseis defined as the first filament in the series to evoke at least oneclear paw-withdrawal out of five applications.

Dark neurons are observed bilaterally within the spinal cord dorsalhorn, particularly in laminae I-II, of rats 8 days after unilateralsciatic nerve ligation as compared with sham operated rats. Variousdoses of differing compounds of Formula I are tested in this model andshow that the Formula I compounds reduce both incidence of dark neuronsand neuropathic pain behavior in CCI rats.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications are intended to be included within the scope of thefollowing claims.

We claim:
 1. A compound of formula I:

or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug,metabolite, stereoisomer, or mixtures thereof, wherein: Y represents theatoms necessary to form a fused 5- to 6-membered, aromatic ornon-aromatic-N-heterocyclic ring, containing 1-3 nitrogen atoms (or 1-2carbocyclic fused rings) wherein Y and any heteroatom(s) therein isunsubstituted or independently substituted with non-interfering hydroxy,amino, nitro, dimethylamino, alkylamino, alkyl, alkenyl, cycloalkyl,cycloalkenyl, aralkyl or aryl substituents; R³ is double bonded oxygen;R², when present, is hydrogen, alkyl, alkenyl, cycloalkyl, cycloalkenyl,aralkyl or aryl; R¹, R⁴, R⁵ and R⁶ are independently hydrogen, alkyl,alkenyl, cycloalkyl, cycloalkenyl, aralkyl or aryl; wherein R², R⁴, R⁵and R⁶ are unsubstituted or independently substituted with a moietyselected from the group consisting of alkyl, alkenyl, alkoxy, phenoxy,benzyloxy, cycloalkyl, cycloalkenyl, hydroxy, carboxy, carbonyl, amino,dimethylamino, alkylamino, amido, cyano, isocyano, nitro, nitroso,nitrilo, isonitrilo, imino, azo, diazo, sulfonyl, sulfoxy, thio,thiocarbonyl, sulfhydryl, halo, haloalkyl, trifluoromethyl and aryl;provided that (i) where R¹, R², R⁴, R⁵ and R⁶ are not each hydrogen whenY is a 5-membered, unsaturated-N-heterocyclic ring; and (ii) when R² ismethyl and R⁴, R⁵ and R⁶ are hydrogen, Y is not methyl or phenyl2-substituted pyrrolyl.
 2. A compound selected from the group consistingof:

or a pharmaceutically acceptable salt, hydrate, ester, solvate, prodrug,metabolite, or stereoisomer thereof.
 3. The compound of claim 1, whereinsaid compound has an IC₅₀ of 100 μM or lower for inhibitingpoly(ADP-ribose) polymerase in vitro.
 4. The compound of claim 1,wherein said compound has an IC₅₀ of 25 μM or lower for inhibitingpoly(ADP-ribose) polymerase in vitro.
 5. A pharmaceutical compositioncomprising a compound of claim 1, and a pharmaceutically acceptablecarrier.
 6. A pharmaceutical composition comprising a compound of claim2 and a pharmaceutically acceptable carrier.
 7. A pharmaceuticalcomposition comprising a compound of claim 3 and a pharmaceuticallyacceptable carrier.
 8. A pharmaceutical composition comprising acompound of claim 4 and a pharmaceutically acceptable carrier.
 9. Thecomposition of claim 5 wherein said composition is administered as asterile solution, suspension or emulsion, in a single or divided dose.10. The composition of claim 5, wherein said composition is administeredas a capsule or tablet containing a single or divided dose of saidcompound.
 11. The composition of claim 5, wherein the carrier comprisesa biodegradable polymer.
 12. The composition of claim 11, wherein thecomposition is a solid implant.
 13. The composition of claim 11, whereinthe biodegradable polymer releases the compound of formula I over aprolonged period of time.
 14. The composition of claim 6, wherein saidcomposition is administered as a sterile solution, suspension oremulsion, in a single or divided dose.
 15. The composition of claim 6,wherein said composition is administered as a capsule or tabletcontaining a single or divided dose of said compound.
 16. Thecomposition of claim 6, wherein the carrier comprises a biodegradablepolymer.
 17. The composition of claim 16, wherein the composition is asolid implant.
 18. The composition of claim 16, wherein thebiodegradable polymer releases the compound of formula I over aprolonged period of time.
 19. The composition of claim 7, wherein saidcomposition is administered as a sterile solution, suspension oremulsion, in a single or divided dose.
 20. The composition of claim 7,wherein said composition is administered as a capsule or tabletcontaining a single or divided dose of said compound.
 21. Thecomposition of claim 7, wherein the carrier comprises a biodegradablepolymer.
 22. The composition of claim 21, wherein the composition is asolid implant.
 23. The composition of claim 2, wherein the biodegradablepolymer releases the compound of formula I over a prolonged period oftime.
 24. The composition of claim 8, wherein said composition isadministered as a sterile solution, suspension or emulsion, in a singleor divided dose.
 25. The composition of claim 8, wherein saidcomposition is administered as a capsule or tablet containing a singleor divided dose of said compound.
 26. The composition of claim 8,wherein the carrier comprises a biodegradable polymer.
 27. Thecomposition of claim 26, wherein the composition is a solid implant. 28.The composition of claim 26, wherein the biodegradable polymer releasesthe compound of formula I over a prolonged period of time.
 29. Thepharmaceutical composition of claim 5 for treatment of diseases orconditions selected from the group consisting of tissue damage resultingfrom cell damage or death due to necrosis or apoptosis, neuronalmediated tissue damage or diseases, neurological disorders andneurodegenerative diseases, vascular stroke, age-related maculardegeneration, AIDS and other immune senescence diseases,atherosclerosis, cachexia, degenerative diseases of skeletal muscleinvolving replicative senescence, head trauma, immune senescence,muscular dystrophy, osteoarthritis, osteoporosis, neuropathic pain,nervous insult, peripheral nerve injury, renal failure, retinal ischemiaand skin aging.
 30. The pharmaceutical composition of claim 6 fortreatment of diseases or conditions selected from the group consistingof tissue damage resulting from cell damage or death due to necrosis orapoptosis, neuronal mediated tissue damage or diseases, neurologicaldisorders and neurodegenerative diseases, vascular stroke, age-relatedmacular degeneration, AIDS and other immune senescence diseases,atherosclerosis, cachexia, degenerative diseases of skeletal muscleinvolving replicative senescence, head trauma, immune senescence,muscular dystrophy, osteoarthritis, osteoporosis, neuropathic pain,nervous insult, peripheral nerve injury, renal failure, retinalischemia, and skin aging.
 31. The pharmaceutical composition of claim 7for treatment of diseases or conditions selected from the groupconsisting of tissue damage resulting from cell damage or death due tonecrosis or apoptosis, neuronal mediated tissue damage or diseases,neurological disorders and neurodegenerative diseases, vascular stroke,age-related macular degeneration, AIDS and other immune senescencediseases, atherosclerosis, cachexia, degenerative diseases of skeletalmuscle involving replicative senescence, head trauma, immune senescence,muscular dystrophy, osteoarthritis, osteoporosis, neuropathic pain,nervous insult, peripheral nerve injury, renal failure, retinalischemia, and skin aging.
 32. The pharmaceutical composition of claim 8for treatment of diseases or conditions selected from the groupconsisting of tissue damage resulting from cell damage or death due tonecrosis or apoptosis, neuronal mediated tissue damage or diseases,neurological disorders and neurodegenerative diseases, vascular stroke,age-related macular degeneration, AIDS and other immune senescencediseases, atherosclerosis, cachexia, degenerative diseases of skeletalmuscle involving replicative senescence, head trauma, immune senescence,muscular dystrophy, osteoarthritis, osteoporosis, neuropathic pain,nervous insult, peripheral nerve injury, renal failure, retinalischemia, and skin aging.
 33. A method of inhibiting PARP activitycomprising administering to a person a composition of claim
 8. 34. Amethod of inhibiting PARP activity comprising administering to a persona composition of claim
 6. 35. A method of inhibiting PARP activitycomprising administering to a person a composition of claim
 27. 36. Amethod of inhibiting PARP activity comprising administering to a persona composition of claim
 8. 37. A compound of claim 1 wherein R¹, R⁴, R⁵and R⁶ are hydrogen, and Y is pyrrolyl which is unsubstituted orsubstituted with at least one substituent selected from the groupconsisting of halo, phenyl and alkoxy substituted phenyl.
 38. A compoundof claim 37 wherein R² is hydrogen.
 39. A compound of claim 37 wherein Yis N-substituted methyl.
 40. A compound of claim 39 wherein R² ishydrogen or methyl.